I bought two 1GB sticks of memory for my MacBook Pro 2.33 GHz Core 2 Duo. I currently have 2 GB, and I wanted 4 GB (this was before I knew about the 3.3 cap). So when the new sticks came, I excitedly opened the back to find that both the expansion slots were already occupied with 1 GB sticks. I had just assumed it would be "built in" memory or something, not taking up my expansion slots! So I'm a little peeved about that. But anyway my question: I'm returning the 2 new sticks. Do I buy one 2GB stick instead, so that I have a 2GB and a 1GB altogether? I know you're supposed to have matched pairs so will this effect performance, or is that not what they mean by matched pairs? Also do you think moving from 2GB to 3GB is significant enough to be noticed? Things have really slowed down since I upgraded to Leopard so I'm assuming it's a RAM thing. Do you think it'll help? Thank ya.