One the ways to get more FPS out of an old videocard is to replace the manufacturers cooling solution with a new, more powerful one.  Virtual-Hideout has a review of Arctic Cooling’s Accelero X1 VGA Cooler, which is an inexpensive cooler that may help you get a few more Mhz out of the GPU or memory.
“With an expected availability of around the end of February 2006 and a proposed MSRP of around $33 USD, I think it’s a pretty good value. I found them to be high quality units with a solid feel and very good cooling while remaining at a very respectable noise level.”

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