Hi,
I have some legally owned DRM WMA files on my computer and I plan to reformat my harddrive and reinstall Windows. So my question is, how would I back up my DRM music so I can still plan them after I reformat my computer? Can i just place the files on a CD and be able to play them later? Or do i have to backup some kind of license files and stuff?

You can back-up your licencse using Windows Media Player but you will need to be connected to the internet to reload it after you reformat. If you still have the original CDs I would suggest that you turn off the protection option in WMP and re-rip your CDs so they don't have any DRM protection on them. If you don't have the originals then you can simply burn each album to an audio cd using WMP burning feature or by using Nero. Most other burning apps won't let you burn DRM protected WMA file even if have a license to be able to burn them.

If you use WMP to burn make a note that it places a mandatory two second gap between each track so if you try to re-rip these burned copies you will have to manually search for the album before you can rip the disc again as the disc will not be recognized by the CDDB or by windowsmedia.com's database.