First off what are you wanting specifically from your mobo? Do you want to xfire or SLI? Onboard graphics or video card? If you aren't looking for anything fancy (like full x16x16 Xfire) then i would say go with the cheap boards, such as the P43's.
Also dont bother with ddr3 ram for the time being, stick with the ddr2.
Another also, 8 gigs of ram would be more then enough (in almost all cases). I have 4 gigs of ram and i dont think my system has ever used all of it. If you are wanting to overclock it would be to your advantage to stick with 4 gigs of ram, as adding more sticks decreases the overclocking potential.