topic. I want to hook my guitar up to it so I'm wondering what I'll need? I've heard people say that I'd need a pre-amp with an ibook, but not on the pb..is this so? I've been thinking of switching to mac for about two years now and this is, I feel the perfect time to do so. the most I can afford is a 15" pb w/sd but I'm leaning more towards a 12" ibook or pb, and advice?