Hang on to System until FS-X

After much thought I have decided to hang on to my old Dell Dimension 8250, P4-2.4ghz, 756 RDRAM, 5900XT-128mb AGP, and wait for FS-X. Since that is almost a year away, would there be any performance increase if I went with a new AGP video card? They are coming down in price and maybe I could squeeze a little more out of the system with little additional investment. I would like to add another 256MB RDRAM but RDRAM is too expensive, especially since I would have to get 512mb.(lack of slots).Suggestions are welcomedThanks,Carl