Some of these posts are so laughable, it's sad and pathetic. I own a PC and an XBox. I've been playing first person shooters since the original Castle Wolfenstein and I can say this right now FROM EXPERIENCE:
Halo is the best FPS ever. Period.
The AI is miles ahead of most FPSs. Anyone who has played Halo seriously knows this. From your grunt mates to the Covenant AI.
For example, if you try to hide from the enemy - and they know you're there - they'll send scouts (usually the cute little grunts) to seek out. Once they find you, the grunts will run away (screaming just things as "He's here!"). They'll lob grenades to flush you out. The little grunts will distract you while the bigger guys take pot shots at you.
Hell, there's no better moment in FPS when a grunt flees, screaming, "He's unstoppable!" or "We're all gonna die!" or when you lob a grenade in their midst, and they all scream "GRENADE!!!!!!!!" When you lob a plasma grenade (that sticks to the enemy), the little grunts will scream around in circles, while the bigger boys will scream into the air a la Predator in frustration - and sometimes run directly at you in a last act of vengeance.
Or how about the little moments like when a grunt will kill and enemy, and then proceed to fire into the corpse, yelling, "YEAH! You think you're so tough?!"
I don't know how come so many high school students are posting here, but coming from this 30-something, trust me - Halo is/was still the best, and has been since Half-Life.
Am I going to get the PC version? Hell, yes - even if I am not assigned to review it. Why?
a) Better graphics. Keep in mind, the PC still does better graphics than any console (that is, resolution, etc.)
b) Multiplayer. 'Nuff said. You ain't played til you're in the back of a Warthog on a CTF map making cover fire for your mates as you whiz along at 60mph.
c) The Story. Sorry, but I still love the story. The music is THE best I've heard in any computer game - yes, better than Half-Life's - especially when the percussion starts up when you enter a particularly tough area.
By the way, the Dreamcast had a keyboard/mouse setup, too. It's not strange. The only reason the XBox doesn't have one (yet) is that Microsoft is afraid of it being called a "PC console" (which it is not - ask any developer.)
For you PC owners who haven't played Halo - you're in for a treat. And trust me, the last, final map may not be all that challenging, but it IS a great climax, full of chaos and a great build up, as the fighting goes on all around you.
For that matter, I just can't wait for Halo 2. Halo 2 + Live! ... (drool...)