I see your problem. If you have access to one, get a Windows XP Installation disc. Insert it into the PC, then power it on and press F11 as quickly as you can, repeatedly. You should get some boot options, and click the one that includes "CD" or "DVD Drive." After you setup the computer, you are ready to go. Don't add a password, just add a simple account with no password. Name it "User" as a placeholder. after you get to the home screen, your files should be removed and you can donate the PC.
If this didn't work, please reply and I can help, as I have a Dell Latitude D530 running XP and I can help, due to these laptops being similar.
Really hope this helps!