I only have the old Xbox to compare Halo with UT, I've never played Halo on a PC or Mac. The thing that frustrates me is my son was awarded this Xbox just this month as part of a charity thing (he was very sick last 2 years and qualified for a few charity goodies) but just as they are dishing out the Xbox 360, Microsoft decide to look good and give a bunch of kiddies their old stock of the older Xbox. Oh well, beggers can't be choosers. So now I have this Xbox, and of course I went and got a "Xbox Classic" (already saying it's an old game) Halo. And you know what I find? It doesn't even have bots in team mode! So if I want to have a half decent game I either have to buy 2 more controllers and then play on an itty bitty quarter TV screen, or give up. UT2004 seems to have more vehicles one can use, and of course you can hold all the weapons at once. I like that. It's also got the redeemer, which has had moments of absolute hysterical screaming when doing multiplayer against a mate. Also, you can command the bots to cover you, jump in a tank as your gunner, etc. So for my money, I'll play through the Halo Campaign with my son, but save for a few "hide and seek" games of Capture the Flag... halo is no good for multiplayer. UT2004 rocks, and I'm heading out to an internet cafe soon with some mates to celebrate my boy coming off chemo... and UT is going to be the game of choice.