What uses will this system have? It kind of makes a difference on the opinion of the system. It would be a huge waste of money for someone just looking for a web browser, email, and word processor system. It looks to be pretty good from a gamer perspective, though the video card is on the lower end of the high end spectrum, soon to be relegated to the upper mid-range level. I would also wonder if the system was going to be run in single or dual channel mode.
For the most part, dual channel memory is just a sinkhole for money, offering little to no benefit performance wise. I liken it to having this beautiful new 8 lane freeway running through town, when pretty much every other road in town is full of potholes, speed bumps, misc junk that fell out the back of some truck, etc. Once you GET to the freeway, you can really cruse, but it's getting to and then on the freeway that's the problem. Communication speeds between RAM and the CPU are the freeway, and communication with every other part of the system would be the roads full of potholes, speed bumps, and various other traffic hazards that greatly limit speed. The hard drive would be like an old country road that's really just a couple of wheel ruts, after it's rained.
So if you don't run the RAM in dual channel mode, you're left with 4GB, and if you have 4GB you should probably be running a 64-bit OS so you can take full advantage of it. That raises a few minor driver related points.
I'm also not entirely sure what the FSB speed is on the Phenom processors, since AMD integrated the memory controller onto the chip die some time back. But RAM timings can be very important with multi-core chips. It's probably safest if your RAM speed is either exactly half, exactly the same, or exactly twice the FSB speed. However, I would go to some place like the Tom's Hardware forums to get more competent advice on that. AMD chips may not be as sensitive to this as Intel chips.
Anyway, the rest seems fine, except a 74GB hard drive seems a bit stingy. With 1TB drives going for under $200US, it seems like you could do better. Unless you plan to have a second higher capacity drive for storage purposes, and that drive is strictly for applications and other things where you might want every minor performance edge you can get.
If it's a gaming system, I'd say it's not too shabby, and for almost everything else, I'd say it's obscenely overpowered.
I am new to building and just want to make sure that I am not missing something before I order this computer. Please don't be to harsh. Thanks in advance.
-AMD Phenom 9950 BLACK EDITION 2.6GHz Socket AM2+ 140W Quad-Core
Processor Model HD995ZFAGHBOX
-CORSAIR CMPSU-750TX 750W ATX12V / EPS12V Power Supply
-Antec Nine Hundred Black Steel ATX Mid Tower Computer Case
-MSI K9A2 Platinum AM2+/AM2 AMD 790FX ATX AMD Motherboard
-BFG Tech BFGE88512GTSE GeForce 8800GTS (G92) 512MB 256-bit GDDR3 PCI
Express 2.0 x16 HDCP Ready SLI Supported Video Card
-CORSAIR DOMINATOR 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066
(PC2 8500) Dual Channel Kit Desktop Memory
-Western Digital Raptor WD740ADFD 74GB 10000 RPM SATA 1.5Gb/s
-Pioneer 20X DVD