Won't work on that version of OSX. Requires 10.6 (Snow Leopard) as a minimum.

To get PP to work, you'll need to upgrade the OS to Snow Leopard. If you can. Many older machines can't, such as the Power PC versions sold before Apple went Intel.

Go to the apple menu (upper left corner) drag down menu and click about this mac. That should tell you what the CPU is. If not Intel, forget using PogoPlug.