Easiest way is to run Ccleaner if you have it. On the header it will show the exact GPU be it AMD, Intel or Nvidia. Then go to the appropriate site to check for updates. Never found GPU updates for laptops to make a difference to performance, though.
From this review Click Here you laptop has a 512MB nVidia 8600M GT. If you are talking about updating the drivers for the graphics card you can go to nVidia web page and install a small program that will detect the drivers and let you know if new drivers are available.