Format the drive and it will be erased -- it is suggested to do it 3 times -- if you want to be safe no one can read easily any leftovers in the layers !
Use this http://dban.sourceforge.net/ Make sure to set it to seven times and nothing...i mean nothing will be able to read the data.:>
try this one: http://www.killdisk.com/ In my opinion, it's the best one out there. Keep us posted and let us know what you decide.
Drive Scrubber http://www.iolo.com/ds/index.cfm O&O Safe Erase (this software secures the recycle bin, as well as being able to completely erase hard drives from boot) http://www.oo-software.com/en/products/oosafeerase/
ok so those will work if i cant get into the computer its self like when i turn it on it says i need administrative password.