The game isnt as demanding as most people make it out to be. Sure, it's incredibly demanding for most people, because most of the people who own computers aren't gamers like us. So for them to bust out with 512MB+ of RAM and at least a 5700 or 9550 in a video card, that's a lot.
But once you get a good card, the game definetly delivers some graphics that no other game has EVER been able to before. What makes this game so good is the quality of the graphics. So if you can get a nice card, DO IT. you won't be disappointed.