Case: Good
Power Unit: Good
Motherboard: Go for the Premium version. Only a few more $ but better components
CPU: Good
Heatsink: Everyone is going for the Thermalright Ultra 120's now, but the scythe will probably do fine.
Memory: Should be fine but you can probably find cheaper. I bought 2x1 gb of corsair 6400c for $90 with rebate.
DVD Writer: Good
Hard Drive: Good
Video Card: Should be able to find for cheaper. Got my ultra for around $600 with rebate from EVGA.
Operating System: I went with Vista Ultimate OEM for $200
Speakers: Should be fine
These components would be great for a good gaming rig for a while. You can always play the waiting game. There is always new stuff coming around the corner, but eventually you have to take the plunge.
X38 mobos should be out within the month if that's something wyou would want to look into. I think the P35 board is fine. That's what I have.
New AMD and Intel chips should be out soon as well, but <$300, how can you go wrong with a quad core.
DDR 3 is still a ways off to be any challenge for DDR2. Price point for DDR2 is excellent.
New Nvidia cards should be out sometime this fall. I've heard November. If you want, get an EVGA card which has the 90 day step up program where you can upgrade your card if something better comes out within the 90 days. But i've also heard the new cards are going to be midrange, not high end, so by the time the 90 days are up, the Ultra will still be at the top of the food chain.
Also, make sure you check the sales section of NCIX:
http://www.ncix.com/promo/promosale....id=session2007
Some of the parts you are looking at may be on sale, and you don't get them for the sale price unless you go through the sale link.