If I offended you by my characterization of your posts, I apologize. Anyway, it would probably be a good idea for other posters to read your posts to this thread and draw their own inferences from them rather than accept mine.
We agree that the old G4 is still quite a serviceable computer. I also agree with your decision to wait for the next MBP update before replacing your old G4. After all, your G4 is still doing a good job, so why not wait and see what's next? That's what I'm doing, too.
I have been looking for a 13 inch laptop. Unfortunately, there is nothing on the market that will work for me. The current 13 inch MBP weighs 4.5 pounds and so is too heavy to satisfy my requirements. The Macbook Air, although extremely appealing in many ways, has only 2Gb of RAM, which cannot be upgraded. That ends the inquiry as far as I am concerned. I need any new laptop I buy, even an ultra lightweight, to have enough RAM to let me run VMware Fusion in Unity mode and Windows from the OS X desktop, simultaneously with OS X apps. I have learned the hard way that 2Gb of RAM is insufficient to allow me to do that comfortably. In particular, the hinge on the 12" feels like it did when it was brand new, whereas on the 15" it seems rather loose and wobbly at this point.
Before anyone suggests it, I am not interested in a Windows laptop because of the inability of Windows machines to conveniently run OS X.