So this would be my first build and I'm looking for some of your expert advice. I'm on pretty flexible budget but I would like to keep it around $1,700 - $1,600.  
 
Video Card:
EVGA 512-P3-N877-AR GeForce 9800 GTX SSC 512MB 256-bit
http://www.newegg.com/Product/Prod [...] 6814130349
 
CPU:
Intel Core 2 Quad Q9450 2.66GHz
 
RAM:
OCZ Reaper HPC 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066
http://www.newegg.com/Product/Prod [...] 6820227289
 
Mobo:
GIGABYTE GA-EX38-DS4 LGA 775 Intel X38
http://www.newegg.com/Product/Prod [...] 6813128089
 
Case:
CoolerMaster Cosmos 1000
 
PSU:
CORSAIR CMPSU-620HX ATX12V v2.2 and EPS12V 2.91 620W Power Supply 100  
http://www.newegg.com/Product/Prod [...] 6817139002
 
OS:
Windows Vista Home Premium x64
 
HDD:
HITACHI Ultrastar A7K1000 0A35771 750GB 7200 RPM 32MB Cache
http://www.newegg.com/Product/Prod [...] 6822145170

Looks good. Although consider the 1TB drive for $30 more. It's 1TB.

The 9800gtx isn't the best value. It's only slightly faster than g92 8800gts. But if you have the money, go for it.

Everything else good as is.

What's the build intended for?