RAW image formats: Which one?

Right, getting into photography (I still cantcall my self a photographer, yet) I have made a few decisions that change the way I take and use my photos. The most important one was to shoot in raw as much as possible. The problem with that is which format?

At the moment my camera (Canon EOS 350D) shoots in Canon’s own proprietary CR2 format. This can be read my PhotoShop CS2 (with updates) and Apples Aperture and iPhoto. But then there is Adobes Digital Negativeformat (DNG). Adobe has released a tool that will convert 100 different RAW formats into, what Adobe is calling an open standard.

My question is: Should I be backing my RAW images up as CR2 file, DNG
files, or a mixture of the both? DNG does have the ability to actually include the original RAW image in with the DNG, and includes a preview in JPEG format too.
Any photographers out there with a comment?