If you have broadband you can't go wrong
Single Player is a little half-baked but entertaining, the ending is just wrong... but you're getting this for the multi-player... right?
If live in a dorm you should be able to system-link over your schools network (since I've never heard of anybody being able to connect to live over their school net)... it's not as convienient as live but there was always somebody up for Halo:CE when I lived in the dorms.
Get Halo 2... Get Broadband... Get Live...