Whilst my iMac is getting slightly long in the tooth at 4 years old, it still has lots of useful life left. The supplied hard disk was getting full, so I decided to replace it. The procedure is straightforward on the revision B G5 iMac, and the drive worked perfectly first time, no jumpers required.
This is a much faster drive than the previous one, also being a pretty fast drive in it's own right. It is also very quiet, and generates less heat - a consideration in the cramped case of the iMac. The only drawback? I shall need a bigger back-up disk at some point.
Overall a great buy and definitely recommended.