For me, it''s about backup of irreplaceables, such as archives or older versions which are very hard to find. I try to make it a habit where every time (especially under Windows) I find a useful application, I backup the archive I downloaded, in case I might need it again or that version is suddenly replaced by a higher version which does the same thing but tweaks a few things and bumps up the OS requirement.

9.1 GB MO disks

Right now all my backups occupy about 170GB on disk, and that is before I should do other things like backup of CDs.

I don't know how all you lot are trifling with multi-terabyte disks I could probably backup every single thing I possibly have on 250GB.