So what you're trying to say is......
Go for the iBook. The MacBook is better, but people at tech forums will always try to convince you to get something better. There's always something better anyway, and they cost more. For some, the extra $300 is worth it, but it's not worth it because internet shopping on a MacBook isn't faster than it is on an iBook.
This will serve your girlfriend's needs just fine. Just check to see if the machine looks really worn out before purchasing.
I have never had nor operated a mac laptop before. I have had several mac towers. How can I check the battery life on the iBook before buying? The guy who is trying to sell it to me doesn't seem like he put much use into the iBook. He was telling me the machine was "loaded" with osx, finder and safari... lol.