I have the same machine and this is what I would highly recommand. For GPU, I bought the BFG Nvidia GeForce GTX275 OC 896MB from Best Buy. Now, there are many versions of GTX275 by multiple developers. Go with the BFG, you can't go wrong with it. Also, the one in Best Buy is the OC (overclocked) version. This card also can be overclocked to OC2 or OCX with the right driver and cooling system. The card uses 2 6-pin and one and the only 16X PCI-E slot on your MOBO. jeffgonth, our machine is unable to do SLI or Crossfire due to only 1 PCI-E 16X limitation. However, any single card will fit just fine and you would have plenty of room, even for proper venilation. Don't go with the ATI 4890. GTX275 will sweep the floor with this card in almost all high end graphics games, including Crysis. Too much research went into me saying this. There is also a GTX285, but due to overheating and graphical problems, its now an outllet item on the Best Buy website. Simply put, this card was performing higher core clock than stated on the box and result in many users to reduce the clock speed to lower setting to be functional. Long story short, the GTX275 is as good as the GTX 285 and costs $50.00 less with no factory defects that I know of. The GTX275 is $229.00. Big bang for the bucks if you ask me. Also, your GPU is as good as its installed driver. Do not install the one that comes with it. For the maximum performance, install Forceware 185.66 vista 64-bit beta driver. This driver will increase the performance of your card to its best capability. With this card, your powersupply must be upgraded as well. The 360W already installed is not going to get you anywhere. I bought the Thermaltake 850W TR2 RX (Black Widow Edition) powersupply from best Buy as well. Plenty of good clean power with minimum heat output. This will fit your 435MT Perfectly with no modifications. It was on sale when I bought it for $149.00, but its back to $179.00 now. Excellent PSU value and perfermance. Also, don't overclock the 920, its already fast. Overclock the GPU if you want, but in small increments and you may have to provide additional cooling to prevent overheating. Finding a card that can be overclocked easily with no defects is just a luck of the draw. Hope that I was somewhat of a help and let me know if you have any addional questions.