Was going to suggest getting a Live Linux CD, booting it and then writing garbage to the HD.
When you delete things from your hard drive under most OS's it doesn't actually remove the data, what it does is remove the reference to the location of all the file bits which, perhaps surprisingly, aren't stored contiguously in one place on the platter of your HD, but are scattered across them. When you delete something it just removes the reference as to where to find these bits to put them all back together. This is why a decent filesystem (i.e. not fat32/NTFS) have much more finer control allowing you to choose the blocksize and level of journaling thats required. I
never have to "defragment" my hard drive as you do under M$-Windoze.
Anyway you have to physically over-write sections of the HD with nonce sense if you truly want to wipe the data from your HD and by the sounds of it thats what dban does. It is a Linux based live CD (based on Ubuntu) that appears to work with both PC and Macs by the
sounds of it.
Probably as simple as making sure you've definitely backed up everything (do this five times over at different times of day, I wiped some 60Gb of music 'cause I thought I'd backed it up and blithely went and deleted it without checking
), then drop the CD, let it boot, and well I was going to say follow the online instructions, but you may have some trouble with that if the screen is foobar'd. Perhaps try plugging in an external monitor and using that to go through the instructions to wipe your HD.
