Without the Bluescreen error is hard to determine why, but I guess may be becaus you're using 4Gb of RAM. Try installing XO/Vista using only 2 Gb, when finish try add the other 2Gb

In addition......

 

In order to get the OS to see and address the 4 Gigs you must take out 2 sticks as GioAguilar stated, leave them aside.  Install windows.  Then install the Microsoft Hotfix below so the additional 2 Gb will be seen and addressed. 

Lots more work but that's microsoft for you.

 

Hotfix download link  (Applies to Vista only)

http://support.microsoft.com/kb/929777  

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VelocityMicro Gamer’s Edge PCX

eVGA nForce 680i SLI Socket 775 A1 version
E6600 2.4 Ghz
4 Gb Corsair Dominator DDR-2 1066 Mhz Heat Xchange
eVGA 8800 GTX
Raptor 10,000 rpm 150 Gb
Dell 2407 LCD
Vista 64 bit/32 bit version

SR45

I'm not crazy and neither am I !
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