Yep, for OC Abit and DFI cant be matched. I suggest getting these mobo's anyways. Dont waste your money on any other brands, besides MSI. MSI make great mobo's too, but are not very flexible for OC.
The big differience between socket 754 and 939, is that 939 runs at the same frequency as 754. While running cooler and faster on the same operating frequency. Thats alot better for OC, and share speed. Another big factor, 939 obviously has more pins. Socket 754 has a very grim future. AMD is going to start pumping everything on 939 boards, makeing 939 ameliorate. One thing thats not really appreciated and under-rated is that socket 939 has dual channel memory only. Witch 754 does not run as.
Dual channel memory is great, and it makes up for the fact that affordable 939 processor's at the moment, dont have 1MB L2 cache. Im speaking about the 3000/3200/3400/3500. Its not a matter of, will they, its a matter of time. The next best thing is the winchester, witch is the new core. The next one should be a sledgehammer or a clawhammer. Witch both of these cores contribute 1MB L2 cache. The 3800's ++ come with 1MB L2 cache. But who can afford a 700$ 3800 sledgehammer...lol not me.
Another huge factor is 754 is not compatible with SLI, and PCI Express. SLI is not important, who can afford more then 1 desirable video card. But PCI-Express is very important. Since you will see more and more PCI-Express cards hit the market, while AGP gradually decrease. PCI-Express is getting utilized, so its plague has started. Over all, PCI-Express is alot better then AGP, and it will soon start yo show us all its results.