Truecrypt 6.0 (and 6.0a shortly after) was recently released, which I just used to do full drive encryption for my new Acer laptop running (aghh) Vista.

Seems to work nicely and now has the ability to hide the real OS and create a decoy OS. So if you are ever forcibly coerced to boot the OS, based on the password you issue at the pre-boot screen, you can boot the decoy and not reveal the real OS.

I'll try to recompile 6.x for Diablo soon and see what happens