Last week's Newsbytes mentioned that PC World would erase a disk for £29.99. Can I recommend Darik's Boot and Nuke program (dban.org) instead? It is almost certainly as effective as PC World's erase, doesn't involve giving your hard disk to a third party, and is free.
William Hudson
DBAN is run from the PC and can be installed on a floppy disk, CD-R, DVD-R, or USB Flash drive: pick one you can boot from. Note that it erases everything, including the hard-drive partition table, so your hard-drive letters will disappear.