I'm new to Apple and I'm trying to understand how my Macbook is using memory. I have 4GB it says I'm using 3.91GB but 1.41GB is inactive. If it's inactive, doesn't that mean it's not being used? It says I only have 88MB free, so that leads me to think I need to upgrade my memory. I'm just concerned that if I do it will say I'm using 7.91GB and 5.41GB is inactive because the inactive memory is queued just waiting to be used. So what does inactive mean, and if these are my normal stats should I upgrade my memory to 8GB?