celogram is right the only FSB: DRAM ratio your MB supports is typical of 533mhz ram. if you have a good cpu you could buy DDR2 800 and overclock the FSB to reach the 800MHz and then you could probaly still decrease the timings on the ram too
i got A-Data RAM from newegg and it OC's all the way up to DDR2 1080 from DDR2 800