Helping people with computers... one answer at a time.
With all the different versions of Windows it's easy to get confused, particularly when the term "upgrade" can actually mean two different things.
I recently read that when released Windows 7 will be offered by Microsoft as an upgrade to Windows XP users, but that they won't be able to actually upgrade their systems. I don't get it how can you not upgrade with an upgrade?
Put another way, when is an upgrade not an upgrade?
In reality, we're talking two different things here, and the same word is being used for both: upgrade.
Let's review what that term means, and then exactly how that maps to exactly what Microsoft may or may not do for Windows XP users.
Caveat: as I write this Windows 7 is not scheduled to be released for several months. Anything, and everything could change. I'm focusing on general terms and concepts here, that I expect will apply, but the details won't be clear until Windows 7 is actually available.
Upgrade Definition #1: what you buy.
Microsoft typically discounts prices for new versions of Windows if you have a previous version. I've seen this called a "license upgrade". Aside from some setup-time checks we'll talk about in a moment, it's the exact same software, just at a discounted price.
This isn't at all uncommon in the software world: many tools, utilities and software packages offer a similar discount when you upgrade from version to version.
Windows actually provides different media:
New Machine - you'll see phrases like "for installation on a new computer" on the box. You can install this on any computer that meets the hardware requirements.
Upgrade - this version requires that there be a pre-existing version of Windows.
In the latter case the setup program may actually check for an old copy of Windows on the disk, or may ask you to provide the original media (CD or DVD) of an old copy of Windows to prove that you did indeed have one.
Other than that, as long as we're talking about the same edition of Windows (Home, Premium, Ultimate, etc.), this setup check is the only difference between the New Machine and Upgrade versions of the product.
Upgrade Definition #2: what you do.
If you have a new machine with an empty/blank hard disk setting up Windows is, by definition, a "clean" install, from scratch, that much is clear.
If you have Windows installed on your machine already, you have a choice to make that I'll boil down to this:
Clean install: this typically involves reformatting/erasing everything on the hard disk and installing Windows from scratch. (There are scenarios where installing into a new, empty partition, or installing into a new installation folder on an existing partition also qualify as a "clean" install, but the effect is the same: all previous options, settings and installed software must be reset and reinstalled into this new, clean installation.)
Upgrade install: in this case the new version of Windows installs itself "on top of", or "in place of" the previously existing version of Windows. The setup program and Windows itself then attempt to preserve or migrate all installed programs settings and behaviour to the best of it's ability. In an ideal world you would upgrade Windows only, and then carry on using all your software exactly as you did prior to the upgrade.
It's important to realize that all this applies regardless of which version you purchased by the first definition of "upgrade" - all you did there was get the exact same software at a discounted price. You can perform an upgrade having purchased the "New Machine" version, and you can perform a clean install (after verifying that a prior version exists) if you got the "Upgrade" package.
Here's where we delve into a little opinion. Upgrades between major versions of Windows can be dicey. While in theory the installation and upgrade process should be seamless and "just work", it's not quite that guaranteed. That's why, for example, I never recommend this type of upgrade process for moving from XP to Vista - the result is often an unstable Vista. However, performing a clean install of Vista on that same machine often results in working OS.
Windows XP to Windows 7?
Apparently Microsoft agrees.
If what you're reporting holds through to Windows 7 release, here's what it means:
Windows XP owners would be eligible to purchase an upgrade version of Windows 7. (Remember, all this does is get you the exact same product at a discounted price.)
Windows XP owners would only be able to use that upgrade version to perform an clean install of Windows 7. After checking your eligibility (confirming that you do indeed have Windows XP), the setup program will probably then reformat your hard disk and install Windows 7 from scratch. An upgrade install just won't be an option.
Apparently Microsoft doesn't want to deal with the complexity of trying to migrate a Windows XP installation to a Windows 7 installation.
And I can't really blame them.
At least they seem to plan on giving you the upgrade price.
Naturally, it's actually more complicated.
I've tried to focus on the basic concepts here, because Microsoft slices and dices Windows versions any number of ways. Some that come to mind include:
Product versions: Home, Professional, Ultimate, what-have-you. These all define the feature set included in the box, nothing more.
Language versions: English, Dutch, Spanish, Japanese, Korean, and more. These define the language, of course, but may also in some cases affect the feature set as well.
OEM versions: In addition to the generic "Retail" package, we have Dell, HP, Lenovo, and many more. Large "Original Equipment Manufacturers", or OEM's, often take Windows and further customize the product to their particular hardware for a more seamless experience for their customers.
And of course add in "New Machine" and "License Upgrade" versions.
Now consider all the possible combinations. "Home, Upgrade, English, Dell" - "Ultimate, New Machine, Korean, HP" - and many more. Each of those is typically a separate product and requires a separate installation media.
That's a lot of combinations.
Not to mention whatever I left out.