Even though Halo 2 shipped for the original Xbox in 2004, Microsoft sees plenty of potential in the upcoming PC version to spur its new Games for Windows initiative. Halo 2, after all, was the biggest selling Xbox game ever made, and it remains incredibly popular on Xbox Live even today. The PC version is being developed by Hired Gun, an internal Microsoft studio working in cooperation with Bungie, and executive producer Jo Clowes was on hand at Microsoft's showcase event at Game Developers Conference to give us our first hands-on time with the single-player portion of the game.
The major difference is that it will look a lot nicer on the PC thanks to the vastly improved resolution and some higher-resolution textures. We had a chance to see it for ourselves by playing the Delta Halo level, and the visuals were so sharp that you could read the fine print on the Master Chief's rocket launcher.
The system requirements for Halo 2 are a bit high considering the Xbox version ran on 2001-era hardware, though you've got to factor in the higher graphical resolutions and OS overhead in the PC version. However, they're fairly modest for a Windows Vista machine. You'll need a 2GHz CPU, 1GB of RAM, and a decent DirectX 9 video card. The game will not use DirectX 10, so you won't need the latest video card to play it. However, you will most definitely need Windows Vista, because Halo 2 will only run on Windows Vista PCs. According to Clowes, that's because the game takes advantage of many Vista-only features, such as rapid install. When you first insert the Halo 2 disc into your PC, you won't have to install the game like you traditionally would a PC game. Instead, like a console game, Halo 2 will begin to load up and you can play immediately while it installs in the background. The PC version will also have support for Games for Windows Live, the PC version of the popular Xbox Live online service that allows for matchmaking, friend tracking, gamerscore, and much more.
As its, Halo 2 is on track for release sometime before the halfway point of the year.
Source : GDC 07: Halo 2 Single-Player Hands-On - PC News at GameSpot