I am a relative newby to the Mac world, especially the G4's. I have a 400 MHz G4 with 256MB of memory and I just bought another 256MB. The memory already installed in the machine is PC100 The new memory I just got is PC133. I assume it is OK to mix and match memry speeds in this machine as the bus is running at 100 MHz. I am sending this email from the machine after I installed the extra 256MB so I assume everything is OK. Is my assumption correct? Thanks in advance for your assistance!