I second Crashplan. I use it to back up a directory of my office machine (2GB at the moment) where I keep all the current project stuff, including Outlook arch

I second Crashplan. I use it to back up a directory of my office machine (2GB at the moment) where I keep all the current project stuff, including Outlook archives for the last 3-years of emails. The whole directory is inside a Truecrypt disk, btw (but I am running Crashplan after mounting the Truecrypt volume, so for Crashplan the files are visible). I did a few (say half a dozen in the last 3-years) restores of a specific file and I did a full restore of the whole directory to a completely different machine (a Mac) due to problems with my old laptop - they replaced the HD and I had to keep working for a couple of days before getting it back. And another full restore when they finally replaced the laptop with a new one. In all these cases it worked without a hitch. I also played a bit with their "backup to a friend's computer" thing, but haven't tested it in depth. Never used their online version, though, so I can't say anything about that.