Need motherboard and processor recommendation

i got into laptops about a year ago, but sold my laptop when i got a new job and because it was too big to carry around comfortably, now i need to focus upgrading my main computer

i want a core 2 duo or amd fx dual core (i prefer the intel, but open to amd as well)

i prefer asus motherboards, but i dont know which chipset is the best, all i want is ddr2 dual channel capability, and pci express, i would like it to support nvidia cards, because ATi is lagging behind right now, and i want to be able to get a dx10 card when they come out

i want to be at about 500 total for both, if worse comes to worse, i want a worse motherboard and faster processor, but would like them both to be nice, although obviously im not looking for the best