9600gt 512mb usues system ram?!!

hey everybody
I used to have an en7600gt 256mb ddr3 before upgrading to 9600gt(512mb gddr3-ECS).and I used to get 3.5 gb of ram(i actually have 4 gigs but sincei'm running a 32bit OS you know the deal...)anyways I upgraded to 9600gt and now I get only 3 gigs of ram!!!
does this card use the system ram?
thx
by the way my os is xp professional version(32bit)
and i've got 2*2gb kingstone bus800 installed on my mobo

thanx I got it.

so that means it uses all 4 gigs of ram when playing games and doing other stuffs?right?

or do I need to upgrade to a 64bit os as soon as possible to utilize all 4 gigs?

The best article I've seen about RAM usage on 32- versus 64-bit Windows is actually right here on Tom's Hardware. http://www.tomshardware.com/review [...] ,1775.html

From what I can tell, the gist of it is, you don't get a straight tradeoff because on 64-bit, the addresses are bigger so the same program takes more RAM to load, and this includes the OS itself. But the other factor is of course, the more RAM, the less switching to the hard drive so the faster everything runs. Benchmarking seems to indicate 32-bit Windows is faster than 64-bit up to about 2 GB of RAM, and either OS is equally fast from 2-3 GB of RAM. Above 3 GB of RAM, 64-bit ends up being faster, and that's not counting the fact that on 32-bit you lose the RAM above 3.6 GB or 3.4 GB or whatever depending on your hardware.

I had to try it out, so I loaded 64-bit Vista (works real good and solves all the driver problems I had on XP). The OS itself seems pokey but everything else runs fine. This was on 4 GB of RAM. And I couldn't bear the suspense so I maxxed out my motherboard to 8 GB. Now I know 1) it has to be faster than before and 2) I couldn't use 32-bit anyway. LOL.

http://www.tomshardware.com/forum/258528-30-explained

Windows has its own list of address that points to where data is stored in RAM. In a 32-bit environment, the size of that address space is 2^32 = 4GB. Any device that requires space in that memory address space eats up some of that 4GB of space, so before you do anything, your motherboard and GPU start causing some of that space to be occupied, leaving less for the rest of the system to use.

The ONLY solution is to upgrade to 64-bits.