Pyros,
Welcome to the intel side
As far as mother boards goes, the Abit BD7II series or the Abit IT7max I or II. I have had the BD7II-R, had to RMA it when it died on me. I upgraded to an IT7maxI right when the II's came out, it saved me about $60 over the new board. The big advantage of the IT7 series over the BD7 series is you get more vrimm to play with. That will help you in a more stable OC, especially if you are going to run your DDR at 3:4. Both boards are great in that you can lock the PCI/AGP.
As far as a PIV CPU, I would hold off until you can get your hands on a 2.26 c1 stepping CPU. What is soo great about a 2.26, it has a 17 multiplier. You can not unlock the new Intel CPU's so you need to start at the lowest multiplier that you can. The 2nd best CPU you could get your hands on would be a 1.8a c1 when they come out. That would give you a multiplier of 18. You might end up with a higher OC over stock with the 1.8 chip, but if you are looking at total system performance you will be happier with the 2.26. The extra FSB will pay off nice with the DDR.
For memory, I would recomend a stick of Corsair XMS PC3200cas2 512. I have a stick of it, and LOVE IT
You can build the system now if you want to. The reason I am recomending that you hold off until the c1 stepping CPU's are available at the lower speeds is that you will have a better chance at a higher OC. The highest speed PIV's are c1 stepping right now, and that is the stepping that they will more then likely run the northwoods out with. Intel is then supposed to move to the prescott core to push past the 4GHz barrier.
Good luck, and keep reaching for higher.
Buzzdog