Its just like anything else.
You can wait for it. Then it hits the market and youll have to take out a loan to afford it...
Or continue to wait for the AM3 to come out so your AM2 drops in price and is also "obsolete".
Guess just all depends on you budget, marital status, your current rig and what your needs are.
Myself, I waited until I was at the point where I COULDNT play the newest games, and ordered the best $2000 could buy ( which still isnt the absolute top of the line, that will cost you at least $4000 ).
As far as waiting for the AM2 because 939 will be "obsolete" .. I dont see it this way. Tons of people have or are still buying 939. And, its been one of AMDS finest offerings IMO. The first AMD chip I bought got outdated much faster than these.
X2 3800 - X2 4800 is an AWESOME buy right now. And I would say the direct opposite, and nows the time to do it
