I have Call of Duty 2.
It was a big screw-up on the part of the developer's (the multiplayer mode, that is). Just goes to show you how far ahead Bungie was in that department with Halo 2.
You would think Activision would try to fix that, whether that means releasing a patch or doing something to the servers on their end. I repeatedly tried to play last night, and was never able to get online.
There's nothing remotely close to Halo 2 on Xbox Live. I'm waiting on the release of Halo 3 before I buy Xbox 360. Being that I'm a college student, I'm a little bit short on cash right now.