I've had the chance to play an Xbox 360 at Wal-Mart as I'm sure much of you had. Boy those are some good graphics. I was playing Call of Duty 2 also. The controls were good but I'm more of an "inverted" type of guy so it was awkward (the horizontal axis was set to regular instead of inverse). But the main thing is this:
It ran at a constant 60 FPS (or more). No studders or anything. On my computer (2 GB of PC3200 RAM, 1.8 GHz Barton 2500+, GeForce 6800 GT 256 MB, etc.) it doesn't run this well. I'm excited about Xbox 360 now. If launch games are looking this good, who knows what the games down the road will look like? I know I shouldn't base an opinion on one experience with a console, but hey, it made me happy. I had a blast playing it and was amazed at the graphics.
To answer your question: I generally upgrade my videocard so I don't have to play games on the lowest details. I've heard countless people "diss" a game because their computers sucked. "Doom 3 sucks those graphics suck omg!!!" (This was when it came out). Yeah, a Radeon 9200 WOULD make Doom 3 suck
If you plan on playing any other computer games in the future (new games), I would upgrade your videocard. Sucks having a processor that powerful and that much RAM to be bottlenecked by a shitfest videocard!