ok, there are a couple motherboard that are good right now. However, you have to choose whether you will be running two graphic cards or just one graphic card.
If you are running two graphic cards, any motherboard with nForce 680i SLI chipset will be good for you. For example,
http://www.newegg.com/Product/Product.aspx?Item=N82E16813188019
OR
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131073
However, if you going to use only one graphic card, any motherboard with P35 chipset will do great for you. For example,
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128048
OR
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128059
(I'm not too sure about the difference between the DS3R and DS3L
)
also, for the processor, core 2 duo will be great for your build. Something like e6750 probably.
Hope this helps.
Good Luck with your build.