Which memory should I choose DDR 400 or DDR2 667 which is better or any suggestions to my hardware list?

I am planning on updating/changing my old PC which was P4 1.8 GHz 2 g ram few days ago my motherboard gives up on me after 6 years of use. My budget is low right now I still want to use my old video card which I guess is still good BFG 6600oc 256mbs AGP. I’m planning on changing my motherboard to http://www.newegg.com/Product/Product.aspx?Item=N82E16813157115 and for processor to http://www.newegg.com/Product/Product.aspx?Item=N82E16819116036 which easily can be OC to about 3.0GHZ with a good heatsink. So I’m not so sure which Memory (ram) to get for best performance DDR 400 or DDR2 667. As for heatsink http://www.newegg.com/Product/Product.aspx?Item=N82E16835186134. That’s all any suggestions are welcome and also is it a good idea to keep my old video card because I picked this motherboard because it has AGP slot.