My dual is working quite well, and gives me better game benchmarks than pretty much any quad would, in most games. Still, that won't last much longer. Most builds are X3 or X4 now.
That's why we are recommending the X3 720 for budget builds so much. It's a nice mix of Ghz and cores once overclocked. You can also get a good crossfire board at a good price for AM2+ or AM3.