Bungie has just announced that they're bringing Halo 2 to the PC.
There's only one catch, you need Windows Vista to be able to play it, for now.
So obviously we'll have to wait 'til Vista comes out before we'll be playing Halo 2 on PC.
Here's the link to the announcement at bungie.net:
I guess a lot of people will buy Windows Vista, just to get to play this game on a PC.