Well it depends on your budget, but here is what I would go with:
ASUS P5E LGA 775 Intel X38
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131219
$224.99
Intel Core 2 Duo E8400 3.0GHz LGA 775 65W
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115037
$194.99
MSI GeForce...