Ram and cpu will probably make the most difference. A 9700pro isn't to new but a new $200 card isnt going to help much with only 512mb of ram and a XP 2000.
<A HREF="http://www.newegg.com/Product/Product.asp?Item=N82E16820145485" target="_new">2x crucial 512MB DDR 333 (PC 2700)</A>
<A HREF="http://www.newegg.com/Product/Product.asp?Item=N82E16819103376" target="_new">AMD Athlon XP 2800+</A>