Backing up to DVD isn't normally the best option. You do a backup today and tomorrow your DVD backup will be out of date.

I'd recommend getting an external USB harddrive (or memory stick depending on the amount of data your talking about), and using a piece of software such as allways sync (http://allwaysync.com/) and setup a backup for your My docs folder to the USB hard drive. Then when you make changed to your My docs folder you just hit sync again, and it replicates the changes to the USB drive to you always have an upto date copy of everything. There are other programs out there that do the same job but the above is what I use and have had no problems with.