Impatient shit, theres a warranty anyway and your not losing money. That would be my main concern, that and the gaming. The first 360's were shitty the new ones do have better hardware. My shit hasn't fucked up on me yet, I would risk it simply because of Live, but the only risk really is not having it for 2 weeks, they give you a free month after anyway too for Live.
Halo 3 should be up there with Gears of War 2, you can't have a Xbox and not play 1 of these.