I'm selling my 5 year old 'Seagate' 20GB hard disk.?

If i 'shift+del' all data, will the buyer still B able 2 recover it. I have vital data stored that i'll be erasing. i 'have' 2 sell it, how do i make sure that the buyer doesn't recover it thru any 'data recovery software'? my vendor says he'll erase it and format it, how do i... show more If i 'shift+del' all data, will the buyer still B able 2 recover it. I have vital data stored that i'll be erasing. i 'have' 2 sell it, how do i make sure that the buyer doesn't recover it thru any 'data recovery software'?
my vendor says he'll erase it and format it, how do i make sure that he has erased it forever?
Update: 'lain N' thanks, 'dzr0001' :I am using Windows XP.
I am selling the hard disc bec my vendor says, if the disc is free of 'bad sectors' he'll pay me atleast 800 Rs.
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