MY PENTIUM 4 SYSTEM runs with a 533 (133) front side bus and a 2.4ghz northwood(1.8) the system is very fast and i did see an improvement in my x-mpeg encoding after i had increased the bus speed to 533mhz.also pc1066 rambus is faster than any 'standard ddr' memory and it brings rambus back to the top in the speed stakes.
From what i have found though at the moment is that many new boards are based on the sis 645dx or the intel845d/e which both utilise DDR memory i havnt seen any decent boards with the 850e apart from the one mentioned above.
regards