How can I give my GPU some of my RAMs memory?

I'm using windows 7.
ATI 6490m 256mb (dedicated memory I think)
I have 4gb of RAM (I'm thinking of upgrading to 8 though) and would like to increase my GPUs memory to 1 GB or 500mb, I hear it's possible to take RAM and give it to the GPU if they have shared memory, how can I do this on windows 7?
thanks in advance, my GPU is bottlenecking my quad core i7 :P

Anonymous2012-04-07T15:56:11Z

You can't.