Its important to keep regular backups of your data, particularly files that are you'd really be upset if you lost (finances, baby pictures, etc). I recently found a free program called Cobian Backup that is designed for making basic file copy or zip archive backups of your files - it won't burn them to CD or DVD but its a good start. Its a little fiddly to get working correctly mainly because there are a large variety of options, but once you do you'll have pretty reliable backups as needed.
What I suggest is creating a Zip backup of either 50mb or 100mb chunks, and if you have the drive space keep about ten days worth. You should schedule it to run every day after work / at night so you've got your important files backed up daily. You should first do one backup to see how much disk space it ends up using, which will help you work out how many CDs or DVDs you'll need later. Once you get it all set up and its working well for a few days, you could then start copying a set of backup files to CD or DVD and putting them in a heat-proof firesafe or safe deposit box, preferably in a different building to your computer just in case of e.g. fire. With a few simple practices like that you shouldn't have too many problems.
I'm going to write up some documentation on how to use it for work, then I'll also post it here.