Ive been building p/c's for a while and i read a lot of reviews and none of them recomend a 256meg card your frame rates wont be more than a frame or 2 higher on the 256 the 128 meg cards are just as fast at 1/2 the cost very little software is writen to utilize the extra memory go to tomhardware.com and read the reviews go to newegg.com and buy the latest chipset you can get for a pci card as a rule of thumb Nvidia is a tad faster but pixilated and an ATI is smoother in my humble oppinion.

http://webpages.charter.net/snafu/ford.jpg

p4 3.2 running at 3.6ghz
ATI 9800 pro flashed to an xt 128 meg
1 gig ram all on a hydro cool 200ex 25 c to 35 c depending on load