Try this utility (Eraser):
http://sourceforge.net/project/showfiles.php?group_id=37015
Download and then burn it to a CD and then install on the PC you want
to erase files on. Use it to erase as much personal data as you can.
Next use your Windows XP CD to delete any and all partitions, create
one small partition (10GB) and format to re-install Windows (for this
purpose no need to activate/re-register the product), create a second
partition using the remaining space available on the drive.
How to do a Clean Install of Windows XP
From Michael Steven's:
http://www.michaelstevenstech.com/cleanxpinstall.html
After re-installing Windows, install Eraser again and use it to wipe
all the free space on the Windows partition and all of the free
(un-used) space on the second partition. Finally once again use the
Windows install CD to delete both partitions.
Note: The more sensitive the data on your PC the more important the
above steps become. As mentioned before only total destruction of the
hard drive is a absolute method.
JS