Reduce the shared memory for Video

have you tried through the bios?

which card do you have?

Windows 7 should automatically reclaim video memory if it needs it. Otherwise, some BIOS can be set to turn off shared memory, but that also depends on the Video card.

I don't think that's a good idea because if you do succeed in doing it, it will reduce the video quality.

What you would be disabling is either the RAM cache of previously calculated screens (which can be cached to avoid having to recalculate them again and again and again...), or the location where video calculations are held directly before being presented on the screen. This behavior depends on your chipset design. Either way, disabling it will either totally give you no images, or give you degraded performance.

The setting is either Bios based or Driver Based. You might be able to turn it off in the bios, but if it is driver based, it is not possible.

http://download.microsoft.com/download/9/c/5/9c5b2167-8017-4bae-9fde-d599bac8184a/GraphicsMemory.doc

My Laptop is lenovo T500,
graphic is mobile intel graphic 4 seriels express family.

what option is in BIOS? I cannot fin them,

I think 256M is more than enough for me since I do not play 3D games.

Shared Video Memory

If it is driver based, you will not be able to disable it, and there is nothing that can be done about this.

but as my picture at the question ,
system says I have 4G installed , 2.96G usable, and when I go to task manager, it only have 3G memory installed,

it hard reserve 1G for shared video. it is  a big issue.

You can't take that picture as a hard fact. That is just the current memory usage it shows, like a "snapshot". If your something in your system requires more RAM to run than the 2.96GB, the OS will manage this and provide the System with some of the RAM that has previously been used by the Grafical system.

See it this way:

What you see in that screen is cached memory for the graphics adapter, this means that it's stored information so that it doesn't have to reload it each time you want to view it. If your system needs to use some of that memory then it will reduce the size of the cache and as the memory frees up again and you use programs/games which require more graphics cache then your system will increase the cache of your graphics adapter again.

The actual amount that is always dedicated to your VGA and which will not be removed from cache is 64mb, this means the cache will shrink to a minimum of 64mb but will use as much as it needs it the memory is not needed by any other software