OK, here are my recommendations.
1. Upgrade the PSU. Going with a low rate power supply unit is like putting a time bomb in your computer. I just recreated your build on Cyberpower and swapped out the Hush 680 watt PSU for a Corsair 650 watt PSU. The efficiency, reliability and features ensure the value of the purchase and better yet the life of your computer.
+$48 above the Hush PSU
2. Upgrade the GPU. The 9800GTX+ will hold back your system graphically. It would THE only bottleneck in your whole system. The HD4870 1 GB or if you must use an nVidia card, the GTX 260.
HD4870 1 GB - + $81 above the 9800 GTX+.
GTX260 - +$71 above the 9800 GTX+.
3. Change the memory. Corsair's Dominator series isn't much better than the XMS series. You can save some cash by going with that instead.
-$29 below the Dominator series.
Total increase = $90-$100 depending on GPU.
Finally, unless 12 GB's of RAM are required, 6 GB's should be looked into. You can save $150 on RAM and $10 on the motherboard by using the Gigabyte board instead of the MSI board.
Total price = $1,325-$1,335 depending on GPU.
The rEVOLution is not being televised
