Not that this seems to be a great issue, but I just wanted to add that if you don't travel alot, go with the 17". I have a 12", and while I love bringing it to school everyday, once I finish school, I would want a 17".
There are so many things people don't consider when choosing their PB. Firstly, while the 12" is super portable for carrying around, its actually quite awkward to use on your lap. I don't do this often, but when I do, its difficult. Why? Because the footprint is so small that I feel as though its going to fall between my legs and hit the ground. It just doesn't feel comfortable. A 15" would fit better than a 12" or 17". I like my 12" though. 🙂
Another consideration: If you're going to go portable, the 15" has a shorter battery life than the 17". Yes, that's right. The 15" has the worst battery life of all the Powerbooks. Same battery as the 12", and the 12" can last for about 4 hours on battery life if you're ONLY using Word. The 15" usually lasts less than 3 hours. The 17" has a bigger battery than the 15" and 12", which compensates for the size. This is one reason for the 1.2lbs difference in weight. It would be worth it for Apple to put in the 17" battery into the 15" and make it a tad bit heavier.
The 1280 x 854 resolution of the 15" isn't THAT much greater than the 1024x768 res of the 12", meaning that it doesn't make that much difference in screen real estate. You may as well get the 17" and get the screen real estate that warrants a laptop size greater than the 12". No point going bigger than the 12" if it isn't that much bigger.