I have two E-macs. One uses the PC133, the other DDR. Check your System Profile to see what Processor and Processor speed you have, that will determine the memory. Also, I had a bad stick of memory that corrupted the OSX install due to repeated lockups and crashes. Once I figured out that it was the memory I had to wipe and reload. So be sure that the memory is spec'd for a Mac. To the first poster who mentioned that the stated max is 1GB RAM but you can put 2GB, where'd you get that particular piece of information? I'm interested to know, as I'd like to do that for my DDR-loaded E-mac, if possible.