Safest and easiest is probably to buy yourself a CD writer. They are pretty cheap now, and a CD has enough space for almost anything. Also a CD (unlike floppies) will not die when left in a cupboard somewhere for a while.
If you really want everything backed up (rather than, say, the My Documents directory) then you'll probably have to go and buy a tape drive - once you've installed Windows, Office etc. and a few other things you've used much more disk space than can be backed up on a single CD. Tapes offer more capacity but aren't as quick or simple as buring a CD. Much more expensive too. I hate them, but YMMV.
[ 13 November 2001: Message edited by: Evo7 ]