i think so! i'm using spectrasonics omnisphere, addictive drums, and hypersonic. omni uses the most ram by far though. opening up 2 instances with some vocals KILLS my computer.
okay sorry, let me try a more thorough explanation...
i'm on a desktop pc with a 2.3 ghz processor, 4gb of ram (3.24 usable), and 54.9 gb of free space. when i open a project with fl studio 9.0, it constantly gives me the error message "out of memory". when i check the memory usage on the top of the screen, it shows a number in the 1900s, which means for some reason or another fl studio is only using 2,000 kb of ram and not 3.24! i could do so much more with that extra gb of ram, but my OS or whatever it is seems to be limiting applications to 2gb of ram.