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A clean install of any operating system assumes that the hard disk is empty. That implies some preparation is required to preserve and transfer data.

If I install Windows 7 on my old XP as a clean installation, is there a way to transfer my data without messing up the new installation?

Yes, there is. In fact, it's the only officially supported way to install Windows 7 on a machine that's running Windows XP.

It simply requires some preparation.

A "clean" install of Windows treats the system hard disk as if it were empty, which of course it can be.

If it's not empty, then a clean install either:

"A 'clean' install of Windows treats the system hard disk as if it were empty ..."
  • makes it empty by reformatting the disk as part of the installation process (which I actually recommend, since the next point is so confusing)


  • ignores everything on the disk and loses track of all installed programs and data files. The files may all still be there, somewhere, but the applications you might have used to access them are not installed as far as the new OS is concerned.

The bottom line is that your data's either gone, or difficult to find.

And in either case, a clean install requires that you now reinstall all the applications you had been using on your machine, from scratch.

By far the best approach is to prepare for your clean install with a full backup of everything. That way, no matter what you may lose as part of the installation process, you'll always have it available from that backup.

As I described in How do I upgrade from XP or Vista to Windows 7?, the steps work out like this:

  • Backup so as not to lose any of your data, and as a place to revert to should your installation below fail. Make sure this works.

  • Install Windows - a clean install, ideally reformatting the hard disk so as not to leave clutter around after the install

  • Install Applications - from their original installation media or downloads

  • Restore your Data - from your backup

The net result of this process is a clean machine, running the new operating system, with all your applications and data transferred safely.

It's a bit of work, and as I said, perhaps the most important step is the preparation.

Article C3905 - October 24, 2009 « »

Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

October 25, 2009 12:33 AM

I do backup my data, but I believe I have an easier solution: keep your data and OS on seperae partitions. That way if you need to install again you only erase your OS partition and the data remains untouched. When you're done reinstalling everything your data will still sit there on that seperate partition.

October 25, 2009 4:33 AM

I made 2 backups (1 image and 1 manual file copy including the entire documents and settings folder), but after installing win7 it was all still there under windows.old. Don't take this as an excuse not to back-up as anything can happen when installing an OS. Use the not hard to find Easy Transfer migwiz.exe from your win7 DVD to back-up your settings and migration will be much easier.

Yes, windows.old is what's left behind if you elect not to reformat your hard disk at installation time. I prefer to use the OS installation as an opportunity to really clean up and remove everything that I'm no longer using and anything that isn't needed for the new system.

Chris Awad
October 26, 2009 11:03 PM

There should definitely be an option for Windows 8 to automatically back up the Users folder during a fresh/clean install. Of course, this would require some outside media as a temp storage space, but it should most definitely be an option.

For now, the windows.old approach does seem to be a huge plus for Windows 7. I find it to be a huge load off of my back to have this method available for people who need a reinstallation, but do not wish to lose any of their data. It saves time and money and automatically backs up everything except for the Windows folder (which should not contain anything more than normal) and the Program Files folder (which even now should could contain nothing but the core of your applications and not their settings, and would require a reinstall anyway during a fresh/clean install).

Please be clear: it is not a backup. All it did was leave files on the hard disk. A backup would copy all files to some other device. I consider it a VERY risk thing to count on for either backups, or for preserving data across an upgrade.

Tom Clark
October 27, 2009 8:31 AM

You might also consider a third party solution such as the one Laplink offers. See

This transfers applications as well as data. It was recently reviewed by Mossberg in the Wallstreet Journal.

I own NO stock in Laplink, but have had good success with their products since they came out with serial cables to allow two PCs to communicate directly.

For $20 it is worth a try. Do backup and follow the other prudent steps as well. If it works correctly you have saved a lot of reinstall and relicense time.

Gord Campbell
October 27, 2009 8:37 AM

Here's a different approach: replace your hard drive and install the new OS on the new drive. Then get an adapter to connect your old hard drive via USB, and copy over your data files from it. The biggest advantage: there is no chance you miss a folder in your "full backup."

October 27, 2009 8:37 AM

Switch to a'll never go through this garbage again..and you'll never look back.

Gord Campbell
October 27, 2009 8:40 AM

You also want to export your browser favorites, then import them into the new browser, and the same for email.

October 27, 2009 9:08 AM

New hard disk for new clean installation, old hard disk into usb caddy and all 'data' files etc there to do with as you wish, works very well, having done a number of reinstallations recently (XP)as long as the 'documents/favourites etc ' files are saved, it is a good opportunity to spring clean your system and get rid of those things/programs you downloaded or installed but never really used, I always download things to a downloaded file before installation, so that I keep the installation files just in case, you can then transfer them to a flash drive and install on another machine, usefull if the other machine is not connected to the web

Bernard Winchester
October 27, 2009 9:24 AM

I agree: I would use Achronis Disk Manager to create a new partition for Windows 7 (say 40GB?), install it there, and then when you are satisfied remove all the non-data files from the other partition and edit the boot properties to remove dual-boot. Alternatively, keep the dual boot as a fall-back in case of problems with Windows 7. I have done this successfully with a Vista installation on an XP machine. It would also be prudent to back up all the data externally first.

Hew Helps
October 27, 2009 11:06 AM

But if one uses a new hard drive and then installs Win 7 to this, re-installs Office, Office activation will see a different hardware configuration and will not activate?

Bob Seeley
October 27, 2009 11:43 AM

Making backups and/or saving data to a seperate partitions are a good idea, but some of that data will do one no good if they can't recall what program created it. Many of us have programs that we don't even remember until we need them. Therefore, might I suggest that folks make a list of their programs for later reference before they do the Windows 7 clean install.

October 27, 2009 12:07 PM

Forget Windows 7 altogether and dual boot Ubuntu and live happily ever after.

Nicholas Gimbrone
October 27, 2009 2:47 PM

ThinkVantage System Migration Assistant v6 supports both XP and Windows 7 and does a quick & easy move of data between levels of Windows (as well as serving as a sort of "poor man's backup" for documents).

steven richards
October 27, 2009 4:46 PM

Switch to a'll never go through this garbage again..and you'll never look back.

Posted by: Billie at October 27, 2009 8:37 AM
Macs change OS's, too. A lot of your data will be unreadable by the mac, too.

Kenneth Black
October 27, 2009 5:27 PM

Why can't I just keep using XP? It works fine

You can.

Renato Morbach
October 27, 2009 7:24 PM

The simpler method is having a partition with the OS and programs, and all data in a different partition or even a second hard drive. You can re-install OS, install a new OS and nothing is goping to happen to your data.

Hal Ross
October 29, 2009 6:42 AM

My friend, Paul, has 11,000 pictures organized carefully in 250 folders in Picasa. When he upgrades to Windows 7 from XP, his backed up pictures will be restored from his external drive or from Carbonite which he just started. My fear for him is that the folder organization within Picasa will lost. Picasa will merely organize the pictures the best it can and his months of careful organization will be lost. Any ideas how to avoid this?

Ken Crook
October 31, 2009 10:13 PM

"Switch to a'll never go through this garbage again"

Wait a minute!

Hasn't Mac scrapped their OS 3 times and processor once.

At least with Windows, programs that ran on previous computers will still run an a new computer.

November 5, 2009 4:53 AM

For Bob Seeley-

Use Belarc advisor to create a list of installed hardware, software, and product keys/serials, prior to your upgrade.
It's free...

Charles Tilley
November 10, 2009 8:01 PM

I agree with Kenneth Black. Why fix what isn't broken? I'll ride XP Pro until the wheels fall off.

And to be totally clear: that's a perfectly reasonable approach. There's no requirement to upgrade.

Frank D
November 24, 2009 5:40 PM

I'm not a religious person, nor do I favor any religion (or non-religion) over any other -- BUT, it seems to me that pushing or recommending that a "Windows" person switch over to a "Mac" is a lot like pushing/recommending a Religion-A person to change his/her religion over to Religion-B, or vice versa. My rationale: they're both *religions* and in practical terms they both seem to do what's expected of them equally well (after all, look at the numerous happy believers on both sides). They both have advantages and disadvantages, strong points and weak points. And I've always seen sense in the maxim, "You can't reason a person out of something he/she hasn't been reasoned into." To a large extent the Windows/Mac divide is just a matter of "religious" upbringing. So please, let's not put down the other's "religion?" Thanks!

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