is there any good HDD wipeing software. it's got to be USB bootable and impossible to recover afterwards. Its just for preparing laptops for a fresh copy of windows to be installed ready for customers
as has been said just use DBAN. By default it does a 3 pass wipe. (1's, 0's, random) but you can use different methods with it as well. It is bootable from a USB but you will need something like linux pendrive installer or something.