About to take the plunge and buy my first laptop (currently have a G5 PPC imac.) I'm planning on using Logic 9, Garageband and Sibelius, and recording live instruments. It will be my main computer, and will be moved about a fair bit. I'm going for a Macbook Pro since Apple decided to remove the Firewire ports from the Macbooks. Any thoughts on minimum spec? I can't decide whether to go for 13" or 15" - and would appreciate any ideas on what extras are really worth the additional cash (I haven't got an unlimited budget.) Many thanks.