If you like to make a backup on the CD/DVD, one the most important thing is the burner application. While Windows XP have a built in burner application, the quality may not satisfy you. Also, not many people uses all the features on the professional edition of Nero. For this purpose, Nero offers Nero Free version which you can get from this site by entering your email address or via RS.
There is limitations on this version though. It contains only simply data burning and disc copying features for CDs and DVDs. Additional features and functionality are available with an upgrade to Nero 9 full version. Well, if your needs are only simple data burning and backup, i think this free edition is enough. It's also smaller in size (~55 MB), compared to the professional edition (~300 MB). Why installing the professional when all you need is just a simple burning features?
Thanks to Nero who provided this free version. It can help reducing piracy