My 754 has dual channel support too. I look at the benchmarks and there isn't much difference between my Athlon 64 3000 (754) and the 64 3000 (939). But still go with 939, the latest.
Actually the sockets don't matter if you want dual channel. It's the CPU, and since AMD integrated their memory controller into the CPU itself (a smart move to reduce latency), it also prevented them from enabling dual channel