Reduce shared memory [bootcamp, Windows 7]

I have an old MacBookPro (2011) (4GB RAM, Graphics NVIDIA GeForce 320M). I have installed Win 7 ultimate (32-bit) using bootcamp. I have a problem with amount of RAM in Windows.

In OS X it utilized all the RAM capacity:

But in Windows it assigns 1290 MB for "Hardware Reserved":

After doing some searches, I believe the major part of the "Harware Reserved" is for "shared memory" for Graphics. The following is taken from NVIDIA Control Panel in Windows:

So my question is: If in fact the reason "hardware reserved" is so big, is because of shared memory for graphics, then what can I do to decrease this shared amount in Windows and have more RAM? Apparently OS X is operating without this amount reserved for shared memory, so it seems it should be possible to decrease this amount and still everything work fine.