I have 2GB of RAM in my G5 iMac (spec below) and when I looked at activity monitor 810mb (ish) of that was used (according to the pie chart). Breaks down like this: 120ish wired 160ish Active 530ish Inactive I have Firefox open-1 window 2 tabs and a 245 mb file being downloaded in the little downloads box (nwn demo) iTunes open, just playing, minimized in the dock and activity monitor open. I am running OS X 3.8 and I'm connected to the internet over a wireless network. Should this much memory be in use? I read that unless I was doing video editing I shouldn't need anymore than 750mb-but I'm doing nothing taxing at the mo and usage is over that!