I installed 4GB RAM specifically to work in GB. My project roughly has about 60 real/software instruments and it's now occasionally freezing, giving me the "Part of the project could not be played" error. Does this mean I've maxed it out? In Preferences, I have everything set to Automatic.
RAM wouldn't help out much with that, playing 60+ tracks with their own settings, effects, and EQ (if that applies), you will be using every bit of what your
processor has. A 2.2GHz processor will be cooking doing that kind of work,
Have you tried locking some of the tracks that do not need to be edited? It will write the tracks to the HD, freeing up the processor.
Also, If you have any other programs (iTunes, Safari, a word processor, Photoshop, etc etc) try closing them. Sometimes when GB gives me that error, I close some programs, and lock a few tracks and it will be just fine after that.