Xbox 2 will have a multicore processor and be able to perform one trillion calculations per second. Not only that, you can use XNA Studio, built on Visual Studio Team System to develop games. Sweetness.
Quoted from the Microsoft press release
XNA StudioMS Press ReleaseQuoted from News.com
XNA Studio is one of the first major products to come out of the XNA Initiative Microsoft announced a year ago to standardize game development across different systems. Developers could use the same XNA tools to create games for Windows PCs, the current Xbox and future versions of the console, Microsoft promised.
XNA Studio is based on Visual Studio Team System, Microsoft's collection of code-writing tools for Windows developers who work in large teams.
XNA Studio will include similar collaboration features meant to facilitate the exchange of code between programmers, designers, quality assurance testers and other members of a development project, Microsoft said in a statement. The software will also introduce a new unified file format to ease sharing of game assets.