for full system backup, the program that really sets the standard is
acronis true image
you can make a bootable cd (with just acronis software on), boot from that and create a full 'image' of your hard drive, you can save it on a hidden partition (that acronis can create for you) or onto a cdrs/dvdrs or onto a usb/firewire hard drive, or a networked pc, it has a very simple gui looks like this..
really awesome software, works really quickly, i think you can download the demo (from say from here
http://www.majorgeeks.com/Acronis_True_Image_d2236.html ), in the program use the 'create bootable media' option, burn it to disc, uninstall the software and just boot from that for free
for backuping up things like documents and media files (aconris does do a whole system backup, so does include these mind) use something like
SyncToy its from microsoft and it's free and simple to use
you can tell it to backup from say C:\Files to E:\Files and it saves the job's you've done before, so next week when you run the C:\Files to E:\Files job, it'll only copy the updated files, saving tons of time (and effort)
http://www.majorgeeks.com/download.php?det=4757 (synctoy download)
-edit
i keep an acronis image of my current setup (i run it say weekly i guess) and have an image of a very basic xp install with no drivers installed incase i want a fresh one (takes about 2 mins to restore this one, wheras an xp install takes about 15-20 mins)