Yeah I had similar feelings when replacing the hard disk in my Indigo iMac. When I heard the crack sound after separating the bottom cover I was sure I'd snapped the tabs, but they were fine.

You won't be able to get Rhapsody on that iMac though. The hardware support isn't there (the Rhapsody DR's were bootstrapped with Mac OS 8 and 8.1). I was going to suggest OS X DP1 as it looks very similar to Rhapsody DR2 but the install notes only mentions beige and B&W G3s. It might take DP2, which is my favourite of the DPs.