[Yuiichi]

I don't know of any games that support a keyboard + mouse with the 360. However, a PS3 and Unreal Tournament 3 will give you the same joy as any PC would as it does support keyboard and mouse as an input method. That game really is pioneering new ground within the console space, having both that feature (which I think is killer) as well as the ability to have mods - a first (I believe) for consoles.