I used to use PwnageTool just fine on my Intel based Snow Leopard (10.6) MacBook. Sadly that machine met with a plumbing leak and is no more.

I now have an Intel Mac Mini with OSX 10.5.8, similarly a G4 iMac (PowerPC) also with 10.5.8 installed. When I run PwnageTool (latest version) on either Mac the DFU button is grayed out and can't be pressed.

From memory both machines have the latest iTunes installed.

Can anyone suggest what's wrong?