Leopards and my Macbook Pro got a bump to 4GB of DDR3 PC8500 RAM over the weekend. My comp simply sings and feels sooo much smoother over the stock 2GB (I thought 2GB would be the minimum). It's like the MBP has more room to breathe now (I've been a Mac user for 9 months now), though with 2GB was no slouch either. Just thought I share this. 4GB is the minimum Leopard should be using!