The biggest advantage the PC has over the Xbox is that you'll be able to view it in resolutions not available to you on Xbox (or even 360 with the HD upgrades). You'll be able to take advantage resolutions up to and including 1920x1200, which provide significantly greater clarity than your original Xbox ever could.
As was stated in a recent interview with one of the newest members of the Bungie team, Matt Priestley, Halo 2 Vista's graphics have been tweaked and optimized for the PC experience. The first thing you'll notice is that the first person weapon models have been given some extra polish. That change alone will make the game look much better, and the change is especially apparent to those of us who've played it on the Xbox since it came out, and aren't used to that level of detail.
Along with that obvious upgrade there're some other more subtle tweaks. The developers have taken advantage of the extra horsepower available to them to enable higher levels of detail at greater distances than were possible on the Xbox. Everything looks incredible from a distance now, the level of detail has been pushed up to the maximum. Regardless of how far you are from the texture, its resolution doesn't "pop" lower as you move away from it.
Also, one of the biggest "pop" drawbacks of the Xbox has been rectified in the Vista version of the game. Remember texture popping in cut scenes? We asked the Halo 2 Vista developers today if they were able to handle that problem and John Ketchpaw briefed us, "I kicked the texture cache square in the -blam!-, so that problem is long gone."
2. You Already Have an HDTV
There are some inherent advantages to using a PC instead of a console. Chief amongst these, from the hardware perspective, is the fact that your monitor is high definition. CRT or LCD - no matter which kind of monitor you have it's going to look much better than your standard definition television. This simplifies things because with your computer setup you never need to worry about all the other dynamics of the home theater setup. You're only three feet away from the monitor at most so you don't need to worry about getting the latest and greatest display for thousands of dollars. Of course with a VGA cable, that's also true of the Xbox 360, but you know what we're getting at.
3. Keyboard vs. Joystick: Your Choice.
Which brings us to the Keyboard vs. Joystick debate . The Xbox 360 controller can plug right into your computer via a USB jack so now you can choose to use the controller that many of you are accustomed to using to play Halo 2. However, many people feel that the mouse and keyboard are the only way to play first person shooters, especially on the PC. Now, with Halo 2 Vista, you've got that option.
Keyboard/mouse fans assert that you have a greater amount of control with the keyboard and mouse than you do with the controller. That's almost certainly true, with regards to potential gains. But you have to weigh that against what you're used to and how long it'd take to get used to that kind of thing if you've never used a PC to play an FPS. It might be worth it if you want to become super hardcore and play to win, but if you want to be a casual gamer then it's probably not worth the time if you've got an Xbox 360 controller lying around.
The Halo 2 single player experience has received the same amount of attention and extra polish that the multiplayer has. Because of this it looks better than ever as well as being just as great an experience as the Xbox version. Those who are new to Halo 2 entirely will hopefully be as riveted by the storyline as the rest of us were the first time we played it. Those who have already had the pleasure might enjoy reliving the experience, now in technicolor. The campaign is certainly worth the replay for even those who've already beaten the game multiple times, if not for the love of the game then to refamiliarize yourself with the storyline before Halo 3.
The Halo 2 Vista multiplayer experience will be everything you expect from a PC game and more. The game itself will be the same game that you know and love but with the improved graphics we already touched on as well as some interface features that we can't talk about yet but upon which we fully expect to see speculated.
Along with that you can expect to see some measure of integration with Microsoft's Live Anywhere service. The way in which the service will be involved and what that means for online play is still semi-secret and dependent upon some variables that are out of our hands. Because of that we can't go into details on this quite yet - other than to say it's a feature we want to do cool things with.
6. Sharing Is Caring
Capturing footage using a PC is much easier than capturing footage using a console. There are ways to capture footage directly to a PC's hard drive as opposed to the capture card method that you must use with a console. This is especially useful for screenshots, as the method to capture them is not generally taxing on your system. This further encourages the community to create cool stuff by enabling them to take higher resolution images than they ever could have captured from the Xbox and using those to create something original.
As far as movies are concerned, the process to capture footage directly to your hard drive is definitely more processor intensive than grabbing a single frame, especially if you're capturing audio too, but it's still feasible for higher-end machines. Not having to use a capture card to do these two things is a huge plus and definitely makes it likelier that people will make cool content like machinima, montages and tricking videos.
Since Vista isn't widely avaialble yet, we can only speculate on the number and type of capture apps available, but if XP is anything to go by, there will be lots.
7. Custom Multiplayer Content.
We do plan to support Halo 2 Vista with a package that will facilitate the creation of multiplayer content. This is perhaps the single most novel aspect of the Halo 2 Vista experience. Bungie has always supported its community and making it easier for them to create custom content was an early goal of Halo 2 Vista.
Once the custom community gets cracking we're sure we'll see some pretty awesome material. There'll be a bunch of maps that look beautiful but aren't too well-designed, there'll be maps that are well-designed but not very pretty and then there'll be the maps that strike the perfect balance and rise above the rest to become as much a staple of the Halo 2 Vista community as the maps that shipped with the game. With any luck.