Remember YMMV (your mileage may vary)
I have a KR7A-RAID and I can only get 142 MHz FSB and its not very stable. I have quality parts, all of which have done 160 FSB CAS 2-2-2 in an Epox 8K7A+. I basically got the same results hard ocp did with their first KR7A but later revisions do overclock better.
The Epox 8K3A+ will run DDR400 if you buy the right Samsung PC2700 and have an unlocked CPU. For some reason this Samsung memory is VERY high quality. On the hardforums most people with 1.6A Northwoods and Epox 4BDA2+ motherboards are running 150 FSB and 3:4 mem ratio giving them DDR 400 memory speeds (PC3200) which is comparable to the performance of rambus.
Normally Abit and Asus have been overclocking kings, but I think Epox is stealing the crown away. If you plan to go AMD (Which is how it seems) then deffinitly get the Epox 8K3A+, almost all of them will be able to hit DDR400 speeds with high quality memory because of their KT333 chipset. The KR7A boards have the KT266a which just isn't always able to reach those speeds.
And if you go Intel get the Epox 4BDA2+ MANY people on the hard forums are reporting successful overclocks with them, and most of the problems are only from power supplys that arn't able to do the job all the way.
If my response is brief and vague its because the info you provided is too!