Saw over at Team Xbox that Microsoft will be releasing a Halo collection for the Xbox, called the Halo Triple Pack, to ship this Oct. 4th.
The set will contain Halo: Combat Evolved, Halo 2, and Halo 2: Multiplayer Map Pack. The collection will retail for $59.99 US, subject to change of course.
If you have an Xbox and for some reason don't have Halo or its sequal, this'd be a great set to pick up.
You can find Team Xbox's article here, and Ebgame's page here.