I' be more tempted to use one of these
http://www.pcworld.co.uk/martprd/sto...4&category_oid=
for backup nowadays. Apart from the fact that you can't scrub your backup because of a scratch on the disk, you just drag and drop the stuff you NEED and all your folder strutures are kept the same so you can find what you want easily. Obviously, you can store more on it too. Backing up to optical disk is soooo 3 years ago.
As far as "windows" goes, I guessing you mean backing up what is on your hard drive. Well, if that is the case, "windows" ain't worth backing up as you would have to do that every time you updated windows in any way and that is a LOT of disks. Also, if you get some malware of some kind on your PC, then that will get backed up too. Not good.
Naah, you know what is "important" (i.e. anything you created yourself, game saves, address book, favourites, the latest drivers. That sort of thing, not anything that has a disk or you can download the program to reinstall it.).
Of course, you can buy an extra (320+Gb) hard disk for your PC, install that and then you can use the "backup" function in XP (start, programs, accessories, system tools, backup) to select what you want backed up, select the new drive and Windows will then create a big file with everything you want kept which can then be restored using the same program should you need to reinstall windows. There are other programs which will do that, and they be free, which can run from the system booting up so you have more options in the case of a failure, that will do the same thing, but you will not be able to view the files and select certain ones. Personally, I use the external drive method above (have 3, one for each desktop and one for laptop) as you also have an easy means of transferring these files to ANY PC easily without the worry of a CD/DVD being scratched (anything less than 2Gb of data goes onto pen drive, hardly use disks nowadays). With the prices of external drives now, it is a bit of a no-brainer in my book as it is far simpler, faster, less susceptible to damage and far more convenient if you take your files anywhere as a 2.5" external drive fits into a jacket pocket.