Amy:
Welcome to Apple Discussions.
First, be sure you have a good, up-to-date backup of your computer or User's Folder.
Connect your external Firewire DVD drive to the computer via firewire.
Power up DVD drive and insert install disk.
Hit the Power button on the computer and hold down the "C" key immediately after the chime.
When booted, select language.
Go to Utilities menu and launch Disk Utility.
Select your HDD (manufacturer ID) in left side bar.
Select First Aid in main panel.
Click Repair Disk Permissions.
After Permissions are repaired Click Repair Disk.
Quit Disk Utility.
Open Installer and begin installation.
Choose to Customize and
deselect Foreign Language Translations and Additional Printer drivers.
Check box to install X11 (Tiger) BSD Subsystems (Panther & earlier).
Proceed with installation.
After installation computer will restart for setup.
After setup, reboot computer.
Go to Applications > Utilities > Disk Utility.
Select your HDD (manufacturer ID) in left side bar.
Select First Aid in main panel.
Click Repair Disk Permissions.
Connect to Internet.
Download and install
10.4.10 Combo update or
Mac OS X 10.4.9 Combo Update (PPC) if you are hesitant about 10.4.10.
Computer will restart after updates.
Go to Applications > Utilities > Disk Utility.
Select your HDD (manufacturer ID) in left side bar.
Select First Aid in main panel.
Click Repair Disk Permissions.
Please do post back with further questions or comments.
Good luck.
cornelius