I have a 2.8C Northwood (800Mhz fsb/hyperthreading). I an AGP X800GTO modded to X800XL and slitghtly overclocked. I figure that is about as fast as I am going to get that system to go. I have had a good experience overclocking my CPU (currently at 3.5GHz on stock voltage). Have you tried overclocking yours?
Be careful, many people see the same number of pins on boards designed for mobile CPUs and think that they are compatible with the old Northwoods. The boards that I have looked at are only compatible with Pentium M, Celeron M, and Core CPUs.
i hate to be the one to tell you guys this, but there is no way you guys are going to get a socket 478 cpu mobo with a pci-e slot (especially being nothwood core as well). pci-e slots were only available with socket lga 775 :roll: