I would definitely choose Corsair VX550W, it's cheap with 5 year warranty. Some 600 Watt PSU's would not be enough to run with one 8800GT or 8800GTS. It depends on how good the PSU is and the Amps on the +12V rail are very good. If you plan to use SLI, the GPU power requirements of the 8800GT's in SLi are 183W (Idle) and 358W (Load In F.E.A.R.) and ~38Amps on the +12V Rail. To clarify, that's total system power consumption. The 8800GT itself only uses about 110-120W of power each at max load. A Q6600 is another 100W or so. The rest of this system will take about another 150W total in a worst-case scenario, so ideally you're really going to use about 370W of power in a worst-case scenario unless you overclocks the heck out of that CPU/Video Card. Since that's about 80% on the +12V rail, you're going to need something with at least 32-35A on the +12V rail, and the VX550 should be perfect. You never want to load the PSU to 100% load because the fan will be spinning up too fast and loud and the components' lifespans will be shortened by running near their capacity. But 3/4 of the max load is fine, and at idle I imagine you'll use only 1/3 of that, or about 10-12A on the +12V. I will first answer your question about MBO and SLi. I chose Asus since I had Asus P4C800Deluxe MBO with my old system (which I sold now). I was more than satisfied with it and it was stable for 4 years along with OC of P4. Asus P5E has a new x38 chipset and supports PCIE 2.0 While I was deciding what to choose for my PC, I planned that I'll go SLi sometime in the future, but decided that I won't after all. The main reason is that GPU industry is developing very fast and I'd rather buy a new card in one year than buy another OLD card to have SLI. The question is to whom will I sell that 2 cards after two years.. (That's just my opinion). So, I won't use SLi and that's why I didn't care will my board support SLi. For instance, and to comment your selection of graphic card, I bought XFX 8800GTS, 640 MB card and was happy for one day although I didn't unpack it yet. I've found out that a new 8800GT was out the other day, which was 150$ cheaper, faster and better than my 8800GTS.. Here are some links that should help you choose 8800GT instead of 8800GTS: http://www.firingsquad.com/hardware/nvidia...nce/default.asp http://www.anandtech.com/video/showdoc.aspx?i=3140&p=1 http://www.vr-zone.com/articles/Nvidia_GeF...iew/5369-1.html http://www.hothardware.com/articles/NVIDIA..._Flight/?page=1