Yeah I am pretty much in the same boat myself wanting to build an AMD system (within the next month or 2) after owning intel stuff for years because I hear lots of good things about the AMD 64 FX chips. I am trying to decide between the old socket 939 because I really want the FX-57 (or any FX chip at a good price) or going to socket AM2. If I go the AM2 route, I will have to settle for a X2 CPU. I thought about Socket F but, I think it's a bit overkill.
I was thinking about getting if I go AM2 is either the 3800+ in the X2 line or an Opty and overclocking them until the pirce on the FX's come down a bit. The mobo that I am thinking about getting is either the ASUS M2N or the M2N32 Deluxe. I have seen 2 different versions of the 3800+ X2. One is the 89W chip and the other is the new 65W chip. I am wondering which chip would be better as in terms of overclocking? or would I be better going with a low end Opty?