What are your ram timings like?? Number of sticks?? Dual channel or single channel mode...This test is extremely bandwidth dependent. Do you have anything else running in the background??
I score a 530KB/s at default 1.8ghz(3000+) with 400ddr at cas2....when I OC it to 2.66ghz (9x296) with ~533ddr the score rises to 690KB/s
Run a sandra memory test and let us know what you get...