Microsoft has finally unveiled the minimum system specification for Halo 2. It's Windows Vista only, but this is hardly the big news here.
The minimum recommended CPU is a 2GHz Pentium 4 class CPU, but interestingly enough, it seems like there will be 64-bit support, as Microsoft also lists x64 support. You will also need a minimum of 1GB of system memory, 7GB of free hard drive space and a DVD-ROM drive.
You will get away with having a DX9 graphics card though, as the minimum requirements are support for Pixel Shader 2.0. Named cards include the Nvidia 6000-series and the ATI x700, anything above this should be powerful enough to play Halo 2.
There is so far no information on what the recommended system specifications are, except that you need Vista.
Halo 2 does of course include support for Games for Windows LIVE for some online action. Included is 23 multiplayer maps as well as a map editor for those that fancy making their own maps.
Halo 2 should be available on the 8th of May in the US and on the 16th of May in Europe.
More info here