LaCie Rugged HD is a solid choice for a bus-powered drive, although I think they only go up to 500 GB at the moment. They have a 1 TB but it's not bus-powered. Firewire 800/400 and USB 2.0. They also have one that hits 7200rpm if you want to use it to edit video clips.
G-Tech is also really solid, so you won't go wrong either way.
From my experience, Time Machine is solid. Depending on how big your HD is on your comp, you may be able to partition it.
When I backup my files I make sure I have multiple copies of the important stuff on different drives to be sure I have them.