It all ready depend on what you want the CPU to do. The AMD X2 are more then capable when paired up with a good vid card to play most of all the current games. Also they are real good in HTPC use, I have 2 939 X2's. I have 4200 in a spair HTPC and using a 4800 in my gaming rig. Both are installed on ASUS A8N-SLI deluxe 939 mobos. But I do intend to replace the 4800 rig with a E6600 conroe when the Nvidia 590 for intel mobos come out . Most of the conroes are just plain faster then any AMD CPU right now.Only AMD that compeats with the conroes (6600,6700,6800EE) is the FX 62, but until the price cut on this brings it into the E6600 range then is price will make it a no go. But 939/AM2 X2s are a bargain right now except for the FX.
EDIT: just rem that the X2's were the fastest cpu's prior to the conroes for home use. Even with the release of the conroes,s does not make the X2's any slower, just that they are not as fast as the newer conroes thats all. :D