So now that im compositing on this new MacPro, I have 14gb of RAM to use. AE is only seeing 3gb, anyone have this problem or is AE locked at 3gb only?

I'm running a PC, and have 4 gigs of RAM.
AE has some crazy presets that were tough to get around on the PC, at first it was only displaying 2gb used, but after some tweaks and going into system files I managed to get the 4gigs up and running.

I'm not sure how to help you on your macbook, but take a look in the manual on memory caches and usage.