Got the bug for a new build, need help with Video Card selection as I am a "new" gamer and this MB does not support SLI, but maybe Crossfire?  
 
All suggestions most welcomed    
 
the pieces:
 
SUPERMICRO MBD-X7DWA-N Dual LGA 771 Intel 5400 Extended ATX Server Motherboard  
Model #: MBD-X7DWA-N
Item #: N82E16813182130R
 
Intel Xeon E5420 Harpertown 2.5GHz LGA 771 80W Quad-Core Processor Model BX80574E5420A - Retail  
Model #: BX80574E5420A
Item #: N82E16819117147 2x
 
Kingston 2GB 240-Pin DDR2 FB-DIMM DDR2 800 (PC2 6400) ECC Fully Buffered Server Memory Model KVR800D2D8F5/2G - Retail  
Model #: KVR800D2D8F5/2G
Item #: N82E16820134649 3x
 
Western Digital Raptor WD740ADFD 74GB 10000 RPM SATA 1.5Gb/s Hard Drive - OEM  
Model #: WD740ADFD 2x
 
Western Digital Caviar SE16 WD5000AAKS 500GB 7200 RPM SATA 3.0Gb/s Hard Drive - OEM  
Model #: WD5000AAKS
Item #: N82E16822136073 4x
 
Microsoft Windows Vista 64-Bit Ultimate for System Builders Single Pack DVD - OEM  
Model #: 66R-00838
Item #: N82E16832116215
 
ARCTIC COOLING Accelero S2 VGA Cooler - Retail  
Model #: ACCELS2
Item #: N82E16835186017 For OC'ng the Video card
 
SAMSUNG 2253BW Black 22" 2ms(GTG) DVI Widescreen LCD Monitor - Retail  
Model #: 2253BW
Item #: N82E16824001268
 
Video Card ??  Something like an Nivadia 8800 GT 512mb to 'OC ??
 
Existing case - CM Stacker, Lite-On DVD-R/RW, NEC 3550A DVD-R/RW, PWR-One 650w EPS-12 PS
 
 
Currently running:
 
Asus PC-DL, 2x 1.6LV Xeon's OC'd 3.2ghz, mod'd Intel Wind Tunnel's w/ 80mm fans, 4gb Geil, 2x WD Raptors 36gb SATA's, 2x  WD 320gb SATA's, 2x Lite-On DVD-R/RW's, XFX Ge6600 256mb Dual DVI 8x AGP, Antec Lan Boy Case, 2x 120mm fans front and back and three more 80mm fans in the case blowing down on both bridges and VR's.
 
Intel P3 Dual Slot-One 700mhz, 1gb Ram
 
Just sold:  Tyan i7505 S2665, 2x 3.06ghz Xeon's (stock) 4gb Kingston, 2x WD Raptors 36gb SATA's, 4x WD 250gb SATA's, 2x Lite-On DVD-R/RW's
 

ROFL, have money to burn? You should get 2 9800gx2 slied before going for dual cpu. It affects gaming performance more. Plus, why dual dual cores for a quad? Why not dual quad cores for octo?

Keep in mind that server motherboard do not support sli or crossfire. Or has overclocking features, for that matter. It's designed for server, not gamers. You should get a Skulltrial dual cpu motherboard, which supports both sli and crossfire, and overclocks like a champ.
http://www.newegg.com/Product/Prod [...] 6813121330

Also, for something so expensive, consider holding it off until end of this month, when 4870 comes out.
http://forums.legitreviews.com/about15370.html

This is a GAMER build ?
Some people just have too much money...
 
That's like $1500 of server hardware (CPUs MB RAM).
And why 6GB RAM?  
Don't you need an even number of RAM modules (1 per processor)?  
That 610W PSU is a bit slim for your build.
 
My advice :
Replace your ($1500) CPUs+Motherboard+RAM  
with this:
ASUS RAMPAGE FORMULA ($300)
Intel QX9650 ($1030)
2x Corsair 4GB DHX C4 kit ($200)
Corsair HX1000W PSU ($300)
XIGMATEK S1283 ($40)
Total : $1900
 
Replace your (optional, but why go cheap):
2x WD740ADFD ($280)
4x WD5000AAKS ($360)
with this:
2x WD1500AAKS ($340)
4x WD6400AAKS ($440, better value + performance)
Total : $780
 
Add HD4870 CF (~$800) at the end of the month and be happy.
 
Grand total : $3500.