Beige G3 question

[Dax Kelson]

I have a 4GB hard disk with OS 9.0 installed on the entire drive.  I would 
like setup as small as possible Mac OS install just so I can use bootX and 
get into YDL.

I've found a 8.5 install CD.  When I boot off of the OS 8.5 install cdrom, 
and double click the installer it says:

 "This program cannot run on your computer.  See the documentation for
more information".

Is this because I already have OS 9 on the hard drive and I need to 
re-initialize it first?

Is this because the 8.5 install CD says that it is for iMacs and it is 
detecting that I have a beige G3?

Any help greatly appreciated.

Dax