You mean you're sticking with this one, the one you picked out before?
MSI K8N SLI-F Socket 939 NVIDIA nForce4 SLI ATX AMD Motherboard - Retail
Specs look good and MSI do make nice motherboards. I owned 2-3 of them before and never had a problem with each one. That will work well with the Athlon 64 3500+ Venice. Nice combo. Now get that 2x512MB DDR400 OCZ Gold or Corsair XMS and dual channel them. Also get the 7800GT video card you want to get now and add another one later. I don't see any problems with CPU not handling it. It will.