Ralph You may be right, but all I know is neither of these new IBM 120 GB's will work in the G4 400 with OS 9.04. Perhaps yours has newer firmware or OS. I just got everything working and won't updating anything until I'm done this one lengthy project. Luckily I have to add a third and fourth drive soon, for video and audio files, and would like to have the option of using 200GB. Lynn Sounds like a load of hooey to me. ATA-6 isn't new. ATA-6 is the spec for Ultra ATA/100. I have an ATA/100 and an ATA/133 in a G4/350 (upgraded to 500MHz) and didn't need a card. This is with the ATA/66 controller on the MB. The only reason you might need an ATA/133 card is to access drives larger than 137GB (48 bit addressing). Also an ATA/133 card should allow you to add four more hard drives, not two. Ralph > I have a G4 400 AGP and tried to add a new 120GB IBM hard drive. The > new IBM's are ATA 6, which my G4 400 AGP will not recognize. Tom > (tech) at OWC says that in order to add a new ATA 6 - I need to use a > PCI Card Ultra ATA/133, which adds 2 more hard drives onto the G4.