Like 4jaw said,take the Hardrive out,they're relitivly cheap to buy a new one and even easier to install. Or like ghetto said and take a good size magnet,That ALWAYS WORKS. Because the harddrive works off magnetic properties,Like a Cassete tape does. And when a program "re-writes" over something,Its taking the
" 1's and 0's ",erasing them,rewriting anouther set of ones and zeros,erasing them,re-writing anouther set,untill its finished. DOD standard is 7 times overwrite,but if you're real worried about information leaking out,do it as many times as the program will let you,or trash the drive. And you can't re-install an O/S from a recovery disk. The recovery disk is basicly a boot disc incase you catch a virus or you can't boot or the machine cant function,the restore disk helps you fix the problem. (Depending on what manufacture created the disk.) It could do a number of different things.