I personally can't see what all the fuss about Halo is about. I've played through most of Halo 2 at a friends house and it doesn't seem that special to me.
Don't worry though, the Xbox 360 comes out way before the PS3, as will Halo 3 (probably) so you'll have ample tme to buy it, try it, beat it and so on before Sony try to look clever by crushing Microsoft.
Chances are you'd also be able to download an emulator for the 360 and download Halo 3...heck, it might even come out on PC for you all...just buy a pad that connects to the computer that is like your Xbox one. And you can get them, believe me.
Threaded Mode