That's what online backup like Mozy, Jungle Disk, etc... are for, backing up
those irreplaceable documents, not the entire system. Mozy, for example, will
backup your desktop, my documents, and custom folders or file extensions you
choose at whatever frequency you want, and can work when idle, so it won't tax
a system. It's basically a document backup system. There's windows and mac
versions available. A user can restore files via the web also, should their
entire system be hosed. Also Mozy is free for the first 2 GBs. What the hell,
I might as well make some affiliate money off this glowing endorsement:
https://mozy.com/?ref=XCY3EB
Here's the non affiliate link:
https://mozy.com/