I dunno about not getting Halo. One of the best experiences I've had playing the X-box was playing halo multi with a buddy. I've played mechassult online too... but playing Halo split screen is great. We would do challenges and stuf too. Like how many grenades we could get to stick in a level, only use certain weapons, stuff like that.
Also, the level design seeems realy well thought out for team tactics, even though it's made for single player. Like, one guy sets up and lays cover from one position, (like say a shield on the opening ship, and another goes through a second hallway and outflanks the enemy.
But definately get mechasualt if you want to play that online. Also, look for some cheap games too. If you can get splinter cell on the cheap, that's a greta buy. At one time BB was selling it for $5. Now you cna get it for $15 with a gamer card. It's definately worth 15.
Also, I dunno if Madden of the latest ESPN NFL is better. I haven't got either. Maybe if someone wants to give a testomonial let's hear it. I always hear "Madden, Madden, Madden." But the 2k games always get excellent if not slightly better reviews. You can pick last years verions Madden 2003 and NFL 2k3 at ebgames new for around $10 if you just want to pick up one on the cheap.