Quote: "Actually the xbox360 use xna with a custom operating system look on wikipedia if you dont beleieve me."
Ahh Wikipedia, the home of pure truth.
Yes, 360 does use a custom OS... which is still based on Windows 2000. I believe for non-developers it explains this on the http://www.microsoft.com/xna website for the xna game studio.
Right now XNA is *only* available for Windows, for development means. It isn't even available to registered developers at this point in time, that's not to say it isn't part of the OS; they just don't feel that it's ready for development.
In-fact I think they're field testing it with XNA Game Studio in the public sector first; at which it only output to Windows for Beta 1. They expect to make it available for professional development in around 6months.
Not that any of that has anything to do with Halo 2. I've seen copies of that available for download on the PC, but don't be fooled on it being some m3g4-h4x0rs or whatever those muppets call it. The one I've been shown that's the most stable is the PC version of Halo, moded to allow dual wield weapons and the Halo 2 maps have been converted. All of the cut-scenes were missing.
I mean it isn't a major project for them to have done given they just needed to convert the media back to x86 compatible stuff; but tbh it's NOT Halo 2... it's like putting all of the Quake 2 media into Quake 1. Possible, but it's not the same game at the end of the day.
Intel Pentium-D 2.8GHz, 512MB DDR2 433, Ati Radeon X1600 Pro 256MB PCI-E, Windows Vista RC1 / XP Professional SP2