I was where you are a week or so ago. I read and read and read these forums and asked a couple of questions and after all that research, Opteron was the only way to go. They OC like crazy (like 33% is common) and have all the other benefits of the X2 line (provided you buy dual core - otherwise, they still overclock like crazy but only have one core).
Most people have probably answered this question a hundred times so it would explain why you have so few responses. But my research has led me to Opty 165 and a DFI Lanparty SLI-DR.
Good luck...
HomeyFoos