If you got the cash go down the 939 road, u wont regret it.
939 boards have a few advantages over 754 ones.
939 boards offer Hyper Transport of 2ghz compared to 1600mhz of the 754.
939 offers a data-rate of 14.4gb per sec compared to 9.6 on 754.
939 offers dual channel 128bit memory controllers, 754 does not.
939 boards are more stable for overclocking.
Oh how i wish i had loadsa spare cash!!