I have the first generation aluminum iMac. I had always thought I might upgrade with this update, but the specs didn't impress me too terribly. I have the ATI Radeon HD 2600 PRO with 256MB memory. Does the $1499 or $1799 model have graphics way better than this? I noticed in the graphs comparing graphics they compare it to a 2400 non-pro 128 MB memory model. Enough to consider an upgrade, or should I just wait until they put quad cores in these or something? The rest of the system is 2.4 GHZ, 4 GB of memory. Plus, I have extra display, so 24-inches I *could* do without for now. Thanks!!