It's going to take a while for me to wait for a quad-core that uses a TDP of 65 watts, or even 45, although I can pay a prenium over a 45 TDP instead of 65.

Otherwise, for good energy efficiency, I'd probably go with an AMD Brisbane X2 BE-2400 with AMD Radeon HD X3850 in an AMD Hybrid Crossfire motherboard. That way, when I'm not playing any games, or if a game doesn't require a high-power video card, the AMD chipset could turn off the descret video card to save energy.

I know the performance and energy efficiency doesn't mix, but this could really be great for me, as I like to play games in a desktop PC, but don't want to raise an electric bill too much.

Overall, after I build a new PC, I'd call it an "Energy Star Gaming PC."

By the way, I have a question: Is it possible to adjust the processor speed and voltage in OverDrive to run at 800MHz at 0.9 volts (or 0.875, if possible, although may only lower the energy consumption by 1 watt or 2)? I have a server with AMD Sempron64 single-core running at 800MHz (Cool'n'Quiet disabled) at 0.875 volts, and at that speed, my server, running Windows Server 2008 RC1, runs pretty stable.

Even though you are testing a CPU against the inferior duo core (just check your own results on the "Penryn vs. Phenom: Two Different Worlds" graph, you also compare the Penryn with the Phenom and not the Quad Opteron series which is the same server cpu league. Its another example of biased view towards one company and not just fair comparison of cpu's for the good of the customer.