Windows 7 comes with a feature which helps you in finding how your computer performance is depending on your hardware configuration i.e. Processor, RAM, graphics, gaming graphics, hard disk etc. Once done even if you upgrade your hardware it wont change automatically.
So in order to re run the Assessment again go to Control Panel\All Control Panel Items\Performance Information and Tools and look for Re-run the assessment link in the same window. This would need administrator privilege but will update. Remember if you get around 3 to 4 like me dont be mus worried as many of us don’t have gaming graphics card it would rank low.