Building a new PC and need help selecting a motherboard and RAM x.x

[heroofnone]

Currently I am looking at buying a PNY GeForce 8800 GTS Video Card (640MB) and a Intel Core 2 Quad Q6600, about the two best in price that can handle higher end graphics from what I've seen.

Next though, I need to select a motherboard and processor. I've been keeping up with vid cards and processors so much that I've neglected to do any research on these in a while. The most I currently know is that I want to go with a DDR2 board, given the issues the bleeding edge technology DDR3 gives.

my current setup:
processor: Intel Core 2 Quad Q6600
Video card: PNY GeForce 8800 GTS Video Card (640MB)
videocard 2: none (considering another GeForce 8800 GTS in the future)
Hard drives: 2 36gig raptors, 1 150 gig raptor
CD/DVD burner: old PATA Ricoh CD burner, ASUS SATA DVD-burner w/ lightscribe
case: generic with fans
power supply: generic 650W
Intended OS: Windows Vista
purpose: work and gaming (Unreal 3 and Hellgate london is coming)
motherboard: ?????????????
RAM: ??????????

Any suggestions are welcome, and I am looking for a range of parts here so I can take the 600+ sting that buying the video card and processor is going to give.

 

[Maziar]

For ram , i recommand : OCZ, CRUCIAL , GEIL
For MOBO :

1_If u want SLI , : P5N32SLI-E or P5N-E SLI

2_P35 : if u want DDR2 and DDR3 : ASUS P5KC
If u want DDR2 : Gigabyte P35 DS3R

those asus boards support next 45nm CPU's :
http://event.asus.com/mb/45nm/

 

[heroofnone]

I like the ASUS P5KC, but a few questions:

is SLI enhance video perfomance enough to make up for the slower bus speed of the RAM?

with SLI and crossfire:
will SLI optimize with Nvidia cards?
and will crossfire optimize with geforce cards?
Do I lose anything (or for that matter, will it even work) when I use 2 vid cards of an opposing brand? (2 geforce cards on a crossfire motherboard, or 2 ATI cards on a SLI board).

Thank you

 

[Maziar]

SLI will work only on nvidia chipsets
Crossifre will only work on ATI chipset

but i have heared some people hack the drivers and use Crossfire on SLI board ,

If u dont play @ 1600x1200 and up , then both Crossfire and SLI arent needed