I hesitate to get involved, but I just want to say -- from personal experience -- linux is usually better for keeping old hardware usable in the modern age in many situations. OSX does not run as fast as Xubuntu on my iMac or iBook - it's not even close. Not to mention that it's a far more supported OS by both the OS developers and application developers than 10.2 or 10.3 which those machines would be stuck with (I'm so tired of 10.4 or higher only apps!)

Also, the PPC port of the linux kernel isn't just some hacked port of x86 code. Linux has been designed to be easy to port to many architectures. It's not the x86 kernel that it was in 1994.

In the end, I say run what you want. I won't complain