Overall it looks pretty good, however I might shuffle a few resources in a few different directions...
First off, the video card seems pretty unbalanced to the rest of the computer. In fact, I'de probably rate it at worse than the 9800 card it looks like you have now. Maybe after my next suggestion or two you can afford to spend more on it...
Next, the power supply is overkill. While it is true that a good power supply will keep your system running smooth, spending 4x as much on your PS than on your video card is rather odd. I'd say go with the next lower down SeaSonic, the 380w, for $77. Save $50, and it is just as good as say.. a 500w no-name... maybe even go with an Antec PSU for a bit less.. an Antec SmartPower 400w can be had on newegg for $55.
And now the ram... You know, people are funny. They think, "hey, why don't i buy faster PC4000 ram so i can overclock my system?"... but the major point in overclocking is to get your computer to go faster without spending major money. The extra fast ram is extra money. I'd reccomend some good PC3200 ram that will likely overclock farther than you could get your processor... And actually Newegg has some
OCZ 2 x 1gb sticks on sale for $141 after a $50 MIR. Good stuff, too.. 2-3-2-5 timing. If not those, then maybe a
Patriot 2x512mb kit. Same timing, for $72 afer a $22 MIR.
As for the motherboard and processor, they seem solid. DFI makes good nForce4 boards, and the opty 165 will do well. I do believe it comes with the new stock heatsink w/ heatpipes, in which case it will be enough to cool it, even with some overclocking.