OS X says I'm using almost 3GB just running Chrome, Adium, Activity Monitor and OS X. 4GB is the bare minimum. I find it stupid Apple even offers 2GB.
Thats seems a lot. I'm not sure how you are using 3gb with those programs. Most people would see those three programs using less than a gb.
I also find it stupid apple choose 2gb on an 1300 dollar computer. Did they really need to cut that corner and charge us 100 dollars more for it.