SuperDuper.

I've used it for 3 years now. It may still be free for the limited version. Don't know, it use to be.

Works perfect and makes a bootable backup if your computer. I carry a small firewire hard drive that has my complete computer on it when I travel. If my computer goes down I plug the hard drive into the Admirals computer and start hers up as if it was mine.

http://www.shirt-pocket.com/SuperDuper/SuperDuperDescription.html