Thomas Ravick, WELCOME ABOARD!
I was going to post a quote from the SHIII manual about laptop cards not being supported, but some people do run the game quite well, including, from PG's example, GWX.
I have a Radeon 9600 card, but only 512MB of RAM, of which only 256MB is cached. Some graphics mods reduce my game to an unacceptable 12 FPM or less, but normally I get 30, even in GWX's harbors. My game also loads in 5-7 minutes, which is long but I can live with it. I also get extreme lag and jerkiness in the control room, but only for the first couple of minutes after the game starts. Once everything is loaded I can play it without complaints.
My upgrade is just around the corner, though.