Double Agent on iMac 20" original core duo

I'm having a little problem with running Tom Clany's Double Agent on my iMac via boot camp on Windows XP. I have an iMac 20" original Core Duo, not the core 2.. And only upgrades is 1gig of ram. Runs the game fine but when I actually start to play the game, the video is choppy, as if its having a hard time. Anyone know what options would be optimal for it? I did the hardware test and it everything has green checks except the ATI X1600 128MB of memory is minimal.

Well I kinda solved my own problem so this can benefit those with Intel Core Duo. It seems there's a nasty bug that slows down this game quite a bit. I think this goes for any Dual Core chips AMD or Intel. With the game running, switch to(not quit) to the desktop and bring up the processes(Ctrl + Alt + Del) and find the Splinter Cell .exe and the processor affinity to utilize only one of the core's instead of both. You should immediately notice a difference in gameplay. I'm really hoping Ubisoft will release a patch soon to fix this.