I'd second Jayson's stand on DVD-R/W for backup. The advantages are even clearer if you're on a Mac using Toast - it has a stellar incremental backup system.
I disagree about storage though...I like DVD-R for storage over CD-R for the capacity. Yeah, they're not $39.99 for a spindle of 100 like CD_R's are, but at 4.7GB per disk, it's a better deal (to me).
Stay away from DVD-RAM, DVD+R, and DVD+R/W...I've had poor experiences with those.
As far as media brand, I flop back and forth between Sony and Memorex.
You didn't ask, but I would also highly recommend that you establish a cataloging system...Again, if you're on a Mac, I think you'll love DiskTracker. It works very much like the Finder's "Find File" function.