gamespot.com reports that the iMac is a very poor choice for anything but the most basic PC gamer due to the X1600, -is this true? They also say that the poor performance of the X1600 is due to lack of dedicated video memory: "[the X1600 which] shares memory with the system itself, isn't going to deliver high frame rates." Is this true? I had wanted to pick up an imac or macbook pro for OSX+ some XP gaming, is this a poor choice? I was under the impression it was at least somewhat comparable to an XBox360...??