OnBoard Graphics And Ram...

That all depends if you have on board video. Motherboards with on board graphics use the system memory but only what is allowed set in the bios. An example is like some dell & HP computers, you go to the bios and the video can only have 1 or 8 mb of memory (I'm sure its higher on the new systems)

But on a new asus board with on board graphics you can go from 16 - 1024 mb of memory for the video. It all depends on the motherboard and the settings for the video will be in the bios not in windows.

If your looking to game then on board video is a no-no. If you can afford a good video card get one. If your looking for a work station setup using graphics such as autocad then a system with on board video will do the trick.

Now on a AGP video card the AGP Aperture Size in the bios can help use some of the system memory for video.
But if your using PCI-Express video card then no it does not.