You couldn't be more wrong or more misguided about me when it comes to my use and upgrade tendencies. You may want to review a few of my posts about Apple before you start coining me as one of their drones.
I didn't refer to your specifics. That is irrelevant.
I referred to upgrade cycles in general, and also about how older Apples - e.g. the first of the Intels, which would be the first machines that can be given a fair shakeout as it's not fair pitting a PB against an MBP of any generation - behave with current software versus how machines of a similar relative vintage behave with Windows, referring to the myth that's common here that Apple software makes machines last longer, or that somehow the machines themselves have more longevity packed into them.
As I said, I've tried both recently and the ~3 year old Mac hardware would be equally (non)viable for mainline duties for me with current OS X software as ~3 year old Windows hardware would in Vista and even XP. Beyond that age... well, I'm sure you're aware of the performance gap between the old Apple Megahertz-Myth supported PPC's and the Intels. They had to switch - even their marketing couldn't compensate for the massive gap that was building.