When I bought my first Mac (12" Powerbook), I thought I didn't need a Superdrive either, but eventually I got into the photo and video editing and now I just purchased a 17" Superdrive model. I don't think there's much difference between the 1.6 and 1.8, except the superdrive, faster bus, and faster G5. But then again, those three components, I feel, justify the upgrade. I purchased from Apple Canada and it was only a $250CAN difference. Also, don't forget, as a student she is eligble for student pricing. So have her take advantage of that.
Brian