Yeah, I'd have to agree that you cannot do video chatting over dialup. It is conceivable that iChat would let you try to do it, but, as the previous poster noted, it's pretty much doomed to failure, because your voice data is going to be competing with your images.
The iSight will, however, work nicely with your iBook. A smaller, USB camera with nice specs to consider is the Logitech Pro Notebook, which I also have and which also comes with a built-in mic and, now, OS X support. I like both. The Logitech is a bit smaller and cheaper; the audio from the iSight is better. The iSight is often maligned for poor low-light capabilities, but the camera itself is fine; iChat seems to reduce its brightness too much - which recent iSight driver updates have fixed a bit.
You have a couple of possible options, though:
(1) Call to a second line in your house, and use the internet dial-up connection to receive images from your iBook, which presumably will be connected to the internet via a different line/access than what you need to call home with. This will allow you slowly changing - but better than nothing - video.
(2) Shoot short clips of yourself and email them home. Not real-time, but a lot better than no images.
I wish you the best of luck in this endeavor. I'm sorry you need to be away so long with no broadband connection to home.
