Video Card:EVGA 640-P2-N829-AR GeForce 8800GTS SSC 640MB 320-bit GDDR3 PCI Express x16(EVGA SSC Edition overclocked at 576MHz)
This GPU is out of date and is slower than a 9600GT, 8800GT 512MB, 8800GTS 512MB, 9800GTX, and 9800GTX+. So if you must go with an EVGA get on of these new designs. As evongugg pointed out the 4850 is faster and matches up to a 9800GTX+ but also is DX10.1 compatible were the Nvidia's are only DX10.
By October tho the new 4850 and 4870's will have 2 GPU's on a single video card so maybe one of those should be your focus.
Case:Raidmax Saggita i don't know this case
PSU:Sunbeam 580W Power Supply id get a corsair a pc&p, anctec, seasonic etc power supply over a sunbeam (since i never read any review about a sunbean power supply..maybe they are good...maybe not???)
Motherboard: DFI LANPARTY DK P35 look good but maybe look for a newer P45 motherboard
Memory:G.SKILL 4GB(2x2GB)DDR2 800 look good
CPU:Intel Core 2 Quad Q6600 Kentsfield look good
Heatsink:ZALMAN CNPS9700 LED 110mm 2 Ball CPU Cooler look at xigmatek s1283 or ocz vendetta 2.... they are interesting
Video Card:EVGA 640-P2-N829-AR GeForce 8800GTS SSC 640MB 320-bit GDDR3 PCI Express x16(EVGA SSC Edition overclocked at 576MHz) an ati 4850 is a better choice i think and probly cheaper and faster
Internal Card Reader:SABRENT CRW-UINB 65-in-1 USB 2.0 Internal Card Reader w/ USB 2.0
DVD Drive:LG Black 22X DVD+R 8X DVD+RW
Monitor:Acer AL1916WAbd Black 19" 5ms Widescreen LCD Monitor
OS:Windows Vista Ultimate 64-bit get the home premium 64-bit and use the money saved to get a bigger screen (22 inch) ?
change psu. ram, cpu, cooler are fine. Card change to a 4850 or 4870, unless you insist on nvidia then get the 9800GTX or 9800GTX+, (the gtx 260 might be okay as well). Get a dvd-rw sata drive. monitor is fine, os is fine. mobo get a p45 or x38/x48 (if you plan to crossfire).