Just got this CPU for my P5Q Deluxe and it's working pretty good. Finally got a decent price quad CPU to 4 ghz. As stated above, PC6400 will do fine for your intended overclock.
As for the motherboard, it doesn't seem to adjust the timings for ram properly. When on "auto" it doesn't compensate for the higher FSB, it just stays the same as detected. So may have to manually set for slower latency as you go higher on the bus.