We ordered a 512 MB Chip for my Powerbook G4, 1.33 GHz from CDW. I usually buy my personal RAM from Other World Computing and have never had a problem. However, our district seems to want to buy from CDW. I just installed the 2nd chip we received (first one locked the computer up) and this one locks up, also. It says it's a SimpleTech chip and that it's 2700 DDR for a Powerbook. Has anyone else experienced this with their Powerbook. I just wonder if it's not a proprietary thing and one has to put in Apple's RAM, which is far too expensive. I really need the extra RAM! It has 512, but I certainly could use some more. Thanks in advance for any info you can give me. :) Nanc "Sorrow looks back. Worry looks around. Faith looks UP!"