You sound like kinda freaking clueless person.I could spend $4k+ on a new moderately high end gaming PC (say a duo core E6700, 8800gts, 2 gig ram) and only be (at best) on par with the power of an Xbox 360 that has 2 year old technology in it.
My rig isn't even half that price and it rapes Xbox360 in every crossplatform game I have played.
1. Oblivion - higher resolution, better graphics, smoother framerate.
2. Lost Planet - same as above.
3. BFME2 - same as above.
4. Quake 4 - same as above.
5. Prey - Same as above.
Well... That was only 5 crossplatform games I have played in a while and now I'm mostly playing Medieval 2: Total War, LotRO, STALKER and HL2: Insurgency and none of those games are even avaible on Xbox360.