[X4U] Installing OSX 10.5.6 on Mini

[Ken Johnson]

I'm trying to install a new. retail copy of OSX 10.5.6 on a Mini -  
1.83GHz, 1G RAM, Core Duo.  Just after the startup ascreen - on the  
screen where you select the Disk on which to install, the Mini disk  
(labelled mini) has a red question mark and brings up a message that  
says You cannot install on ths device, repartition as 'GUID Partition  
Table'.

I did that (now I have an empty Disk labelled 'GUID Partition Table" -  
and still get the exact same message.

Any ideas?  - Ken