Jack <gsxrawd at uia.net> writes: > Looking to add more RAM but don't know what I need. > Does my G4 Powerbook 550 mhz use PC133, PC2100 DDR or..... It requires a PC100 SO-DIMM, *not* ECC. PC133 is OK too; it will run at the same speed as PC100 in your computer, so buy whatever is the cheapest. Additionally, 667 and faster 15" PBG4s require PC133. The 12" AlBook requires PC2100, and the 17" AlBook requires PC2700. Kynan Shook kshook at mac.com http://homepage.mac.com/kshook/index.html