The higher that you can get your FSB the better but, you also want to watch the overall speed. The reason that you want a higher FSB is so that more information can be passed throught the RAM and the entire system bus can have more bandwith. BUT depending on what motherboard you have you can only take the FSB so high before your PCI bus becomes unstable, 37-38 Mhz is the limit for the PCI bus. Most new boards will have a PCI lock out also knowen as a infintant divider that the PCI bus will go no higher than 33Mhz. The older boards have a accaul dividvisor that you can set and rise your PCI bus speed but will have a limit on your highest FSB speed. So the higher FSB you can get the better but some times you have to trade some FSb for over all speed, when it comes to that its mainly what proforms better for you.