2gb of ram is not enough for 1680x1050 gaming?

I'm confuse with the statement '2gb is enough for vista gaming'. just to make sure..will crysis get less to none stuttering if i upgraded my ram from 2gb to 3gb?since x86 architecture won't use up to 4gb, 3gb probably would be enough. right now, my vista x86 uses 31-33% physical memory from 2gb ram.

i played crysis for 30min-1hour.then exited,desktop stop responding for few secs..black screen,but still manage to move cursor around.once it back to normal,i started task manager.physical memory shows OS using only 18%!!after a while it returns to 31-33%.already ran disk defragment,clean driver installation(uninstall driver,reboot in safe mode then remove driver files,reinstall in normal mode etc..),registry cleaner,ccleaner etc etc.

sorry for my bad english.

e6550 @2.8ghz
1x2gb mushkin enhanced 667mhz
320gb sata westen digital
gigabyte superb 550w
hd4850
resolution 1680x1050. run crysis in high specs with no AA

2GB of ram is usually enough, but crysis is a bit of an exception to the rules. It will make use of 4GB of ram, and would benefit from an x64 OS. but upgrading to 3GB should give you better performance, as long as you run the ram in dual channel mode.