Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
Over at Crucial or OWC you can check which hardware (including RAM) is compatible with your machine and buy it.

If you click on the Apple icon in the top left corner of your screen and click 'About this Mac', you should find enough information to get looking on those websites.
Be sure to check out your specs because it's impossible for you to have a 9600M if you bought it over a year ago.
 
I apologize.

I of course have the 8600m gfx card. Thank you very much for correcting me.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.