Deleting Personal Information from Your PC

Reader Linus Huang asks: I have an old Windows XP Pro laptop which I want to give to an acquaintance. How could I go about safely deleting my data and all other localizations while leaving the OS intact and the system immediately usable? Unfortunately I don't have the XP installation discs (I acquired the system from a used computer store) so I can't just wipe the hard drive and reinstall XP from scratch.

There's no 100 percent foolproof, super-reliable way to do what you're proposing without wiping the hard drive, but since you're giving the computer to a friend, I think we can get you close. Here's what I recommend you do, step by step. (All of the tools mentioned here are free.)

1. Run anti-spyware applications, including Ad-Aware and Spyware Doctor (both free; get Spyware Doctor in the Google Pack, just unselect the other options), in their most secure modes. This will help delete any personally identifiable tracking cookies.
2. Uninstall everything you can. Getting rid of applications (especially third-party web browsers like Firefox) is a good first step (just use the Add or Remove Programs control panel), as uninstalling will often take with them personalization information. It will also make it easier to delete data files, which we'll get to in a moment. Don't remove anything critical for system operation, like the touchpad driver.
3. Delete data files. Hopefully most of your data is in the My Documents folder, but scour the hard drive, especially the C:\ root directory and the C:\Documents and Settings directory for wayward files. Next search through the C:\Program Files directory and delete any remnants of programs that you uninstalled in step 2. Just delete the whole folder. This is the most important step, so spend time on it.
4. Delete Internet Explorer user data. Microsoft offers a series of tutorials on how to delete cookie files no matter which browser you have. Assuming you're running IE7, though, you'll want to purge all user information (especially stored passwords) using the Tools > Delete Browsing History function. Just click Delete All to scrub it away. Though not a problem with modern browsers, you should also run an index.dat hidden file remover as discussed in this post, just in case.
5. Run CCleaner. This will scrub the registry for you, removing as much personal data as possible along the way.
6. Delete all user accounts except one. Do this in the User Accounts control panel.
7. Look in the Start Menu for the "My Recent Documents" folder. Clear this folder by following the instructions on this page.
8. Empty the trash.
9. Wipe free space. Use BCWipe (see screenshot) to scrub out all the free space in the drive. This way, files you deleted won't be able to be recovered.

You're finally done!

This is indeed a pretty involved process and, as discussed, there's no guarantee it will get every single shred of personal data off your system. It'll get most of it, but probably not everything, so it's a good idea to make sure you can't hunt down an XP installation disc or a system restore disc before doing this all by hand. You could also try installing an Ubuntu Linux operating system instead, which would leave the computer perfectly operable, just not with Windows.