Off topic - imac os X

[T Molnar]

Sorry off topic but I need some help.

I wanted to install OS X 10.2 version (educational free version) on my 
daughters Older Imac G3 500 Mhz/ >300 mb ram machine.

It's running 9.2 right now.  I did the firmware update, but the 
installer when it highlights the hard drive there is the red 
exclamation mark on the drive icon
meaning the hd is not deemed suitable for installation.  There is a 
very old beta OS X from a few years back on the hd.
I thought about totally reformatting the drive etc..but haven't done 
that yet.

Any suggestions on how to install the OS X on this? I used the same 
disks to install OS X on some even older B&W g3 350 mhz towers running 
8.6, but this imac's hd doesn't show up as suitable for install.

Suggestions welcome

thanks
tim