Whats the last OS X that supported Power PC?
Solution 1:
Snow Leopard (OS X 10.6) is also the first Mac OS release since the introduction of System 7.1.2 that does not support the PowerPC architecture, as Apple now intends to focus on its current line of Intel-based products.
Thus OS X supported PowerPC up to and including version 10.5 (Leopard).
Solution 2:
10.5 Leopard is the last to support PowerPC as far as I know:
http://en.wikipedia.org/wiki/Mac_OS_X