Okay so I was just browsing the apple site specs for the newly revised powerbooks. I have the previous version, 15 inch 1.5 gigs. Under audio and video I was confused as to the differences between a few items.

Audio line in (minijack) (12- and 15-inch models)
Headphone out (minijack) (12- and 15-inch models)
Combined optical digital input/audio line in (minijack) (17-inch model)
Combined optical digital output/headphone out (minijack) (17-inch model)
Built-in stereo speakers with midrange-enhancing third speaker (12-inch and 15-inch models)
Two built-in stereo speakers (17-inch model)

What I am confused about is what are those things that are on the 17 inch model, (the combined optical..) like whats different about those?

Also, I assume the previous version had the same speakers, the midrange enhancing one. Where on the pb is the third speaker? And why does the 17 inch model only have the two?? Thanks, sorry for so many questions!