I'd say an NF4 board with an Athlon 64 4000+ (San Diego single-core) for a personal Windows gaming rig. I have an Abit Fatal1ty AN8 (high quality board, but way overpriced and VDIMM limited to 2.80v).
After the initial NF4 teething process, a couple of boards I've played with give great bang for buck: Abit's AN8 Ultra & DFI's Lanparty UT, both in the $125 ballpark. Go with the Abit if you're not a tweaker; it's rock solid as soon as you update the BIOS to 17. The Lanparty UT's a great overclocker, but it'll take you a while to get it purring just right. The DFI only has 2 PCI slots, though.
Both boards are picky about memory, so hit a couple enthusiast forums to get the scoop on what works best. If you already have DDR400 or better, you'll be fine as long as you tweak the memory timings. I'm currently running 2 x 1GB OCZ DDR400 sticks at Cas2-3-2-5 1T and default voltages with no problems.