Best overclocking board is the <A HREF="http://gamershq.madonion.com/compare2k1.shtml?2692208" target="_new">TH7-II</A> Im able to hit a 2.6Ghz@160FSB with stability. The TH7-II has options to increase vcore, decrease multipliers, and FSB increasements of 1Mhz. 255 is the max possible FSB, I have reached 250FSB.
The P4T-E is a good overclocking board to 133FSB, very high stability and actually faster than the TH7-II at the same speed. to get beyond 133FSB you have to use the motherboard jumpers and there are no settings listed beyond 133FSb so you have to start at #6 and test each setting thru #10. sadly when using the motherboard jumpers you cannot increase vcore. so this is not the ideal board for the 1.6A if you plan on 133+ FSB speeds. same goes for the P4M266 and SiS650 chipsets(these boards have offset CPU in the retention mech).
The Via and SiS chipsets are very poor overclockers, avoid these boards. The Via chipset I tested did not have vcore adjustments and the SiS645 board did have vcore settings but did not work.
The P4B266 (i845D chipset) is a very good overclocking board but takes a hit in performance with the DDR SDRAM. The P4B266 has vcore adjustments and memory voltage adjustments.