Okay this is a slot loading iMac G3. There's no need for Xpostfacto at all. All slot loaders are supported up until 10.4.11 natively.
What you DO need to do is read this:

And install the appropriate update.

Click to expand...

Oh. Thank you!! I wonder if that's why it kept giving me the error (-2).

Now I have to install OS 9, again and work my way up to 9.2.2. I can do that while I tidy up my room.

RE: The firmware is already 4.1.9f. What to do now? It won't let me install 10.3 from the OS X install disc. I guess I'll give my friend back his disc and go buy one myself. Where to look for Tiger (or Panther or Jaguar) and not spend too much? Thanks.