Enable graphics card in virtualbox

I recently bought a new laptop with following configuration

• CPU: Intel i5 2450
• RAM: 8 GB DDR3
• GPU: NVIDIA GeForce GTX 520 1GB

I've setup a virtual machine using virtualbox with windows 7 as guest. I want to use my host's graphics card but the virtual machine shows only 128 mb of video memory

I am using Bumblebee and start the virtual machine using

 $ optirun VBoxManage startvm "Windows 7"

Tell me the best way to use my graphics card for virtual machine acceleration?

Like almost everything in a virtual machine the graphics card is also virtual You can still access the hardware graphics acceleration, but it is to a limited extent only (one of the limitations is the max of 128 MB RAM.)

To make use of those 3D features available choose 3D acceleration in the Display settings of your virtual machine. In addition you will need guest additions to provide a driver for the virtual graphics adapter

For the experimental feature of passing a PCI card to Virtual Box (which may work with few graphic cards only) see.

• How to use NVIDIA GeForce M310 on Ubuntu 12.10 running as guest in VirtualBox?