Why do you need to type when you are recording it? Or is someone chatting on aim durring class... tisk tisk.
iSights are expensive, but are very very nice. I was really impressed by the picture quality when I used one. If you don't think you are going to use the video I don't see what the point of it would be then.
I would try one out first, if you haven't used one head out to the mayfair mall in milwaukee, they have an apple store (CompUSA might have em too)
On a some what related note, I wanted to get an iSight, but then my Mom would be bugging me to do video chats with her :-/