Hi. I had a Geforce 8600GTs 256mb card on one of my systems with 2GB of RAM and windows 7 32-bit. Windows used 512MB of that 2GB of RAM as shared virtual graphics memory. I now have put in another stick of 2GB RAM and installed windows 7 46-bit. Windows properties said that I have 4GB ram installed, but only 3gb usable for some reason, so I went to nvidia graphics adapter properties and saw that there was like 1256mb graphics memory on my video card now, instead of the usual 768mb... Is there any way to change the amount of video shared ram used , or is geforce just a RAM hog and I need to switch back to radeon?
No, you need to switch to a card that does not use shared RAM. You will get the same story with ATI. If you are considering a new card, might as well get one that does not do that (ergo; any modern card).
the shared graphics memory should not reduce the amount of memory the system sees, you only see 3gb because you are using a 32bit os. To be able to use 4gb you need to use a 64bit os.
it's just how the os/system aportions system ram, doesn't effect anything. As long as it's a 64 bit os you get to use all your memory available whenever the vram runs out, avilable system ram for the video card is is whatever is not already in use.