Depends on that you want to backup.. if it just data (i.e. Word files, games saves, XXX pics..) a plain CD-R will do the job. Considering that in event of failure you own the CD's for the program files and the OS.. so you can reinstall again..
If you want to create an image on your entire comp.. try using Adaptecs software. Or if you have the money.. and are excentric enough.. buy another HD.. and use Norton Ghost or Clone.. dont remember the name.. and make an exact image of the current HD.
Be and let others be as well!
I second Henrik! Ghost is plastic and fast. I archive partition to file image, then burn *.gho to cdrom along with a copy of ghost...(to be really trick, make cdrom bootable)
Disk to Disk, it'll transfer .5 gb per minute on fast pcs.
If you have a network, take a look at PCR Dist...
If your drive is partitioned, you can create an image file of the C: drive, drop it down to D: as 'Cimage.gho'.
With high compression, you can get c: and nearly a gb of c's contents onto a cdr.
Ghost only works in a dos enviornment.