more likely to be lack of processor power tbh. 2gb should be enough ram really, ive only got 756 and i can get away with a few instances of massive/absynth/sylenth etc along with plenty of audio tracks and quite a lot of vst fx and my shit machine is ancient now.
what operating system are you using? (im guessing youre not mac) xp is still the most tweakable for audio work, well worth installing if youre on a low powered machine (if youre using vista you might as well bin it now tbh

). theres a good list of things you can switch off here
http://tarekith.com/assets/XPTweaks.htm makes a big difference.
if you have a low powered comp getting rid of all the shit on there thats not necessary for production is essential
also what soundcard/AI are you using? if you dont have one are you using asio4all? (not ideal but works an might help a bit)