Thanks for all the great info! I was planning on a 120 using the ATA hook up. Now when it comes to shopping for the drive I can use any of the leading brands? Does it need to be designed for a Mac system?
Hi David - to quote my own experience, the 80 Gb in my G3 b/w is a Seagate upgrade that came with the 2-hand machine, the 40 Gb is an IBM which I bought 2-hand online and reformatted HFS, and installed OS 9.2.2 from the CD I bought. Neither drive has given me one bit of bother.
So no, you don't need to buy a Mac-specific hard drive, not that one exists. [Apple uses a range of drive brands inside its machines.] The main suppliers of smaller drives are Hitachi, Samsung, Seagate and Western Digital. A quick search shows that, in this country at least, WD are the only ones making a 120 Gb 3.5" drive.
Smaller capacity drives are becoming increasingly expensive nowadays because there is so little demand for them, but if I were buying I'd get a Hitachi (IBM), even 2-hand. They're quiet and they run a bit cooler (not really an issue inside a tower). Others might recommend Seagate or WD.
Whatever, have a heap of fun with that G3/G4. They were darned good computers in their day, and are still robust and efficient.