How about not focusing on destroying and focus on workarounds?

Do a good clean up of your current workstation and get rid of everything on there. Then wipe the slack space and cluster tips with the strongest possible. I've found eraser to be VERY good. I've not been able to recover any data using their strongest wipe. And thats using tools that the pros use. (not electron microscopes)
http://www.tolvanen.com/eraser/ I'm pretty sure this is the one.

Then... Why not just bring in your own laptop or PDA? They can't touch that one, right?
Heck, the new palm has a 4gb HD on it.
Don't connect it to their network and you can use it all you want?

Or, use a live bootable CD (any knoppix varient) which doesn't touch the hard drive (it uses a ramdisk). Use a removable flash drive to store your data. It has your games, and multimedia programs, word processors, etc. all right there on the live cd. You'll just have to reboot to your normal OS for your normal work?