as Captjon said, presume you mean the newer macbook? Wouldn't bother with the old ibook (which has a PPC processor and not the latest intel ones)
The white, cheapest macbook will do you perfectly well, its a very good laptop (exactly the same as the base macbook pro, apart from lack of SD card reader and the screens not quite as good albeit barely noticeable) and if you're in education or know someone, get them to buy it on the uni network, and you get approx 15% off! (you can buy it from home on the education website but the discount is less). refurb computers are also fine, you basically just dont get the fancy cardboard box, apart from that its fully functioning and has a full warranty.
http://store.apple.com/uk/product/FB990B/A?mco=MTA4MzIzMzA
Thats a good deal!