I believe reformatting a drive removes all previous files etc. as far as most individuals are concerned, but the data etc can still be recovered using specialist software. A better solution is to use software like Eraser that can be set to overwrite the drive multiple times with random 0s and 1s. If you are really worried about your data and you are disposing of a PC, use MkI hardware to destroy the HD.
I do not want to dispose of the hard-drive, but want to use it 'after having a few problems', and eventually having to do a complete re-format of the computer. Some 'problems' still seem to appear or are present after the reformat or repair via XP.
With regards to Erasure, I have used this in the past, but I now have a more commercial product available, which I have yet to test.
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