Do you have access to a unix based system or only windows? I test drives using badblocks (with destructive write on), it writes a specific sequence all over the drives, looks for mistakes (and tells you if it finds any) then writes a different sequence all over it. Any data on the drive is annihilated unsurprisingly. It took about two days to test a 750gb samsung of mine (it passed), and it certainly sounded like it was being thrashed.
Free of course. I ran it from an ubuntu live usb.
