No offense, but why are you asking online? That's pretty logical. If you don't need it, then sure, sell it. If you think you still need it, then don't. There's not much to it..
I'd get the xbox first just because I like xbox, but that's still up to you...doesn't matter which order heh..which will you use more often..
My younger brother just picked up the 360 last nite, along with the game fight night: round 3. I am completely impressed with the console, and the game. The part that got me the most was, the wireless controllers have a light on them that tells you which "player" you are ie 1, 2, 3, or 4. At the same time, you can turn the xbox on and off with the controller, and open/close the disc tray. Needless to say, I believe for once Microsoft did very well on this system, and outdid themselves. It just seems to be a flawless piece of work.