Mainstream capability

Depends on if it will be a 100% port with no real change (like the first 2 were) or if they will actually do some updating. The wasn't that amazing and is fairly far behind current Xbox 360 titles.

I would say it will play it, just with the settings turned down. Whenever the hell it comes out that is.
 
Have they even announced a PC port yet?
If so I'd say an HD4770 will definitely be able to play it fine at some combination of resolution and settings.
Shouldn't really matter anyways as Halo is rather lackluster when compared to the FPS options you have on PC.
 
One of those things where everyone knows it is coming and there are currently enough rumors to suggest a possible end of year or Q1 of next year release.

Personally the series died with Halo 1. It was a great game, Halo 2 was....eh...but had some nice things about it, still left a bad taste in my mouth. Halo 3....was a pile of crap and I can't wait for the day all my friends stop demanding I come over and play or saying it is the reason I need a 360.

Bad story, same old game play (though they messed up dual wielding really bad) and not all that great of graphics. ODST is got a much better story, but still suffers from same game play (well it is a bit different but not enough to not feel samey)
 
I never much cared for 2, and I bought 3 a while ago, but played the first level and haven't picked it up since.

I did, however, play the multiplayer on 2 with a lot of my friends at LAN parties. A 250 kill rockets/brute shots/grenades match on Foundation (smallest map in the game) with 8-16 people is a mess, but it's the most fun you'll have on that game, especially if the people that are playing are creative when it comes to names.