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When re-using a hard drive, erasing the old system information is certainly a good idea. The best approach might be to backup and reformat.

Maybe an unusual question concerning an external USB drive. (Win XP Pro sp3 updated) I took a 300 GB HDD out of a failed computer (also a Win XP Pro sp3) and plugged it into a USB toaster. It has been running great as my laptop's 'F' drive for a couple of years now. My question is about the old System 'Windows' and program files left on the drive from the old PC. When I run a Full scan using MS Security Essentials, Malwarebytes, or Super Anti-Spyware, it takes quite a bit of time to crank through all those old PC software components. When I originally took the old HDD, there were data files that I wanted to retrieve at that time, so I did not reformat the drive. My question is can I safely remove the old PC system files on the 'F' drive and how can I identify them? Thank you for your consideration and thank you for your informative Ask Leo emails.

In this excerpt from Answercast #24, I look at an old hard drive that is being used as a data drive F and suggest ways to clean it up.

Cleaning an old hard drive

The approach that I take in situations like that is to basically do something along the lines of what you started to do:

  • I would scour the drive for the data files that I wanted to preserve.

  • I would copy them off and then I would reformat the drive.

The bottom line is that it's going to be significantly easier for you to identify the files that you care about – your data files – than it is for you to be able to identify what is and is not a system file. One might think that one could start with just the Windows folder and delete everything in it and by and large, that's true.

However, It is possible (it's unusual, but it's possible) that for some reason you may have something of your own that happened to get left in the Windows folder tree. As a result, I'm hesitant to recommend that as an approach... and it really only takes care of the Windows folder.

Documents and settings

Things get significantly more complex when you start looking at documents and settings. There, by definition, you are going to have files that you care about – your data files – intermixed with files that are presented by or have been created by the system: sometimes large files which potentially include things like the registry.

My strong recommendation is to approach this a little bit differently.

  • Extract all the data files that you know of – that you can –from that hard disk.
  • Then reformat.

Backup first

If for whatever reason you are concerned that you might not catch something you wanted later, back the drive up first. Make a backup image of that drive and squirrel that away somewhere so that you know that no matter what you delete from it today, you could potentially go back and get something that you missed later.

Article C5430 - June 6, 2012 « »

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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.

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1 Comment
June 8, 2012 10:49 AM

I resuced a HD from one of my dead computers that had Xp Pro on it. I recovered all the data I wanted but I was denied deleting the system files or a format even in Safe Mode. Windows doing CYA? I resorted to a hard drive shredder I found in Major Geeks and got myself a 250 MB blank drive.

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