Oh, far from it! The hard drive I'm currently using has a capacity of about 80 gb, and that's on the small side as hard drives go. Even though there's less than 15 gb of data on it, that would still fill up 15 of the flash cards that I normally use for backup.

I have a DOS program (a .bat file) set up to handle my backups. At the end of each session, I run it. It checks in the folders that I've specified (such as My Documents) and copies to the flash drive all files that have changed since they were last backed up. Once a month or so, I burn a copy of everything on the flash drive to a CDR. If there's almost enough data on the flash drive to fill the CDR I delete the oldest files, the ones that have already been burned to several CDRs.

I back up my own data but not Windows nor any other software that I have an installation CD for. If I lose any of those from the hard drive, I'd much rather reinstall them from the original CD than from my own backup attempts.

I do save copies of software that I download, and burn those to CDR. What I save, though, is not the installed program (which can be very large) but what I call the "installer" -- the thing I actually downloaded, usually a self-extracting ZIP file that installs the software, creates any necessary folders for it, updates the registry, puts an icon on the desktop, and does whatever else is needed to get the software ready to run. In case of a hard drive crash, I want to be ready to reinstall everything that I've put on that hard drive since it was new.