Snow Leopard (Mac OS X 10.6)\’s system requirements are:

• Mac computer with an Intel processor
• 1GB of memory
• 5GB of available disk space
• DVD drive for installation

So do not consider running Snow Leopard on any PPC machines… It simply will not work…
But PowerPC (PPC) applications will work with the Rosetta translation layer, as they have been in Mac OS X 10.5…