I believe Anandtech and Tom's both have done reviews that show the current 200MHZ FSB chips can almost all be overclocked with the 133 mhz FSB, but you need to be able to drop the multiplier back to keep the overall speed from getting too high. IE if I had such a board instead of 9x100 it'd be more like 6x133 or 6.5x133...seems to work quite well, the only limitation was the clock generator/northbridges on the old boards, not the chips themselves...the low speed durons <ie 600s> might be able to nail 900 or so without a multiplier change on boards that dont support changing the multiplier due to their higher overclockability
