I believe you are doing one of two things, (not sure if you are aware of it or not), you are either looking at one desktop 3200+ and one mobile 3200+, or one 3200+ 754 socket and one 939 socket 3200+.
Right now the socket 754 will save you some money. Some people would prefer the 939, because that will supposedly be the socket AMD is sticking with. However, I think by the time you want to upgrade your CPU again, there will be enough new hardware features out to make you want to upgrade your motherboard again. Its up to you, but at the moment I would go with teh 754 to save a little money.
My Desktop: <A HREF="http://Mr5oh.tripod.com/pc.html" target="_new">http://Mr5oh.tripod.com/pc.html</A>