mvc said:
I can't remember for sure, but I thought some 10.4 installer discs won't install on systems they weren't made for, i.e PowerMac installer disks not working on iBooks. (If this is completely wrong, do please correct me before I send the O.P. in the wrong direction)
This is correct. It's very inconsistent so far as I can tell, but at least some "came with computer" discs will only install on the machine they came with (or maybe something similar).
Also, as said, if it's an *updater* disc, not a full install, it will refuse to install on any disk that does not have a previous version of the MacOS on it. The solution to this is usually to use the discs that came with your computer to reinstall whatever OS the computer came with, then use the updater disc to install the latest version (doing an "erase and install", since there's nothing on the disk anyway).
Since I'm running Tiger, here's exactly what the Disk utility will say, just so you can confirm what you've done:
First, click on the line on the left that says "93.2GB Somemodelname" (or something very similar to that; it's probably the only disk in the list), and make sure you've selected the un-indented item, not anything underneath it.
Then, click the "Partition" tab on the left. From there, select "1 Partition" from the "Volume Scheme" popup list. Make sure that "Mac OS Extended (Journaled)" is selected from the "Format" popup on the right. The size box should automatically say something close to "93.20GB", since it should automatically make one large partiton the same size as the drive. You can type a name in the "Name" box if you want, or just leave it.
Finally, click the "Partition" button down in the bottom right corner; it should ask you if you're sure you want to erase the disk, and you should of course click yes (or ok, or whatever).
You will then see a progress bar for a few seconds, and when it's finished you should now see an indented name listed underneath the drive's listing over on the right; it will probably be called "Untitled" or whatever name you gave it; it's not important as long as it is there.
Now you can quit Disk Utility and try to install the OS. When I did exactly what you're trying to do, I needed to restart once after formatting the disk, even though I shouldn't have had to; apparently the installer only recognizes disks that were ready to install when it is first started.
Hopefully that gets you pointed in the right direction. Good luck!