The early MacMini's all took PC133 DIMMs. It wasn't until the USB 2.0 version that DDR came into play. The last 2 revisions of the eMac took DDR RAM. The very last rev had an increase in the maximum RAM from 1 GB to 2GB.

eMac



G4 Processor

700/800 MHz G4
PC133 RAM
Max RAM 1GB

800 MHz/1.0 GHz G4 (ATI Graphics)
PC133 RAM
Max RAM 1GB

1.0/1.25 GHz G4 (USB 2.0)
PC2700 DDR RAM
Max RAM 1GB

1.42 GHz G4
PC2700 DDR RAM
Max RAM 2 GB