Halo PC has a lot to offer that the Xbox version doesn't have.
The Campaign is the same but all the changes are in multiplayer. In multiplayer you have "9" new maps to play on,which makes the total around 19 maps or so. That still isn't enough for you, you wanna know how good the Gameplay is?? Well the gameplay is just plain incredible. If you haven't played the Xbox version and were waiting for the PC version let me fill you in on the story. You are the last of your kind, a Spartan (i won't go into detail about what a spartan is), and you have to stop the Covenant from activating Halo. I would go farther in depth but then there would be quite a few spoilers. Ok i'm just gonna talk about the graphics real quick now, if you've seen the Xbox version of Halo you'll notice a difference in graphics with a high end graphics card Things do look better. Ok now onto multiplayer. Multiplayer has 3 new features!!!! that's right "3" that aren't in the xbox version. First there is the addition of the Fuel Rod Gun/Cannon which hunters have, and Black armored grunts have in the last level of Halo called The Maw. It can be a very powerful weapon when used right. The next addition is the Flame Thrower. The Flame Thrower isn't really an ideal weapon for most maps but when you get in close quarters combat (you have to be fairly close) this weapon can be very useful, but be careful get to close to the fire and you get burned too (you just lose some of your shield). And the 3rd additon was a pilotable banshee in multiplayer. However ppl who use banshees in multiplayer are often reffered to as noobs.
I won't go into much detail about what to look out for cause there are a lot of well just think up a couple of sware words and there you go that what a lot of people are like on Halo PC.
Oh and the game even offers LAN and Online multiplayer but no co-op.
This game is a must buy for even the owner of the Xbox verson.