Is this a good build?

I have found all the parts online, I just want to double check everything is compatible and whatnot. I don't have a hard drive picked yet but i'm going to try to get one with 10000RPM and serial ata II. I have several serial ata cables. Other than the hard drive speakers and mouse and keyboard, is there anything else I need? I'm planning on using the computer on hardcore gaming.

Here's the specs

Windows Vista Home Premium 64-bit
Antec Nine Hundred Steel ATX Mid Tower Computer Case
MSI - P35 LGA775 ATX 4DDR2 8GB-PCIEX16 2PCI GBE SATA2
Intel Core 2 Quad Q6600
EVGA GeForce 8800GT
OCZ PC2-6400 2GB DDR2
XION Simple Power 630W ATX Power Supply
Pioneer DVR 115DBK (I coundn't find one with Serial ata II...do they exsist?)

I got all this for around 800$. Is that a good price? Am I going to need more power on anything?