No difference mate, just if you can purchase a socket AM2 mobo, you can obviously get the newer processors that AMD decide to bring out. last time i checked AM2 is socket 940, so a 939 processor will run in this socket. Hope this helps lad.
well conroe is leading atm but thats because they are 65 nm processors, when amd bring out their next gen processors (in am2) they will be 65nm and then they will rival conroe. bit off the subject but thought id let you know anyways in case your considering getting a cheap am2 now so you can upgrade to next gen, (in bout three months)