I have two external hard drives, and was trying to keep one at my office, the other at home. I was also trying to backup weekly. But I probably backed up about 5 times total. When Sam mentioned dropbox.com on his blog, I decided to give it a try. (It is free, after all.)
I think I like it enough to be willing to pay for more storage when I hit my free limit.
If you're interested in dropbox.com (I'm sure there are other good options out there), you can give me some more free storage by using this link to join. I think you get an extra 250Meg for using a link like this, too.
I once had a hard drive crash and burn, on an almost new computer. The warranty got me a new hard drive, but the papers I had written for some lit courses I was taking - gone forever. However you like to do your backups, if you haven't done it recently, go do it!
*I just now set up a file sharing folder, put my manuscript in it, and invited someone to look at it. That was the 5th thing in a list of steps they'd recommended. It got me another 250Meg free.