I purchase my Dual 2.5 GHz G5 with 1.0 GB (2x512MB) RAM from Apple (so I wouldn't be stuck with any 256MB memory sticks, and purchased a second 1.0 GB (2x512MB) RAM from Crucial.com. My system is properly showing 2.0GB RAM and has been perfectly stable since receiving it last Thursday. I've used Crucial RAM for years now, in my Macs and my PCs (and even in my HP LaserJet 1200 printer) with ZERO problems.