Halo 2 is Vista only and is still DX9. Dont count on something Vista only being DX10 only unless u have information stating its DX10.
Originally posted by: Matt2
Only if the game is developed with an alternate DX9 rendering path.
99% of the first DX10 games will allow DX9 cards to play, but eventually, they'll be DX10 only.
Halo2 is an example of a DX10 only game. I think Alan Wake might be DX10 only as well. I read somewhere that Alan Wake was "Vista Only" which leads me to believe that it is for DX10 only.
From Gamespot.com interview
http://www.gamespot.com/pc/action/halo2/news.html?sid=6166892&mode=previewshttp://www.gamespot.com/pc/action/halo2/news.html?sid=6166892&mode=previews
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.