I really need to understand this RAM and speed stuff.

Here's my dilemma, my laptop runs on:

- Windows 7 Ultimate(64 bit) on an x64-based processor with 4GB RAM(2.65GB usable).

Now I upgraded to 6GB RAM and it still has the "2.65GB usable" stuff. I however noticed that the rating for the graphics and calculation speed increased by a whole point i.e 4.5 to 5.5. 

What could be causing this and how can it be fixed??

We had a topic of such a nature but it was inconclusive.