So is this a Mac we're talking about here or a Windows box?
Either way, perhaps something like
CrashPlan?
I know I'm one of the few online backup proponents here, but I'm a firm believer in getting at least one backup OUT of the building. Putting a second drive in your machine only protects against single disk failure or things like accidental erasures. You aren't protected against things that could affect the entire computer like fire, flood, theft, power surge, etc. It sounds like I'm selling you insurance, and that's basically what I'm trying to do. Insure your data and get it the hell out of your home!
The primary knock on these services is usually how much time it takes to upload the data, and that's true. It does take a long while. In that case, figure out some other sort of off-site solution that's easy enough for you to do regularly. A
Pogoplug is a pretty cool solution too, and while I don't know the specifics of how this might work, you could copy all your data on-site before you set it up remotely, thus eliminating the long initial backup and only doing differentials. The only thing you need is the Pogoplug, a hard drive, and a friend willing to let you use some bandwidth
Anyway, sorry to go off on this rant. It's just that you wouldn't believe the percentage of clients I have who turn down my offer to set them up with any sort of backup solution, and then they encounter a problem that results in lost data. I have a good success story of a customer who had me in to set up Mozy, and four months later a pipe burst directly above the computer, utterly destroying it down to the HDD. It took mere minutes to get it all back.