Installing Tiger (errors, & "oh I just want to see my desktop again")

Question

So.
In order to install Tiger 10.4 I had to first install 10.3 onto my 10.2.8 iMac.
Tonight I upgraded 10.2.8 to 10.3, successfully.
Then I tried to upgrade 10.3 to 10.4.
At the end of the game I received the message "There were errors installing 10.4. Please try installing again."
Installing again produces the same message.
But if I try to give up and restart from the internal hard drive, my only option is to select 10.4 on the internal hard drive, so obviously an unperfect version has latched on to it.
If I select this then I cannot reach my desktop, but do get a long text message which begins with "panic" and ends with "panic: We are hanging here..." [I can include a more exact version of the message when I see it again].
I have run Disk Utility> First Aid> Repair Disk, but I believe there were no necessary repairs that could be found.
Nonetheless I am now trying to install 10.4 again, though now my iMac is making these little hard-working clicking noises during the process.
So I'll update this if anything changes, but as of now
My question is:
-How do I successfully install 10.4, or
-How do I rid the computer of this flawed version of 10.4, or
-How do I reinstall 10.3 at this point?
I just want to get back to being OK/ seeing my desktop.
At this point I am not sure how to eject the installation DVD, as the eject key on the keyboard's not doing it.
Thank you.

Answer 1

Update:
OK Well I got 10.3 re-installed alright (although the screen looks a little different-- everything on the desktop seems slightly bigger and less sharply defined).
I have yet to re-try 10.4, but I'm not sure what to do differently. I'll look at it again tomorrow perhaps there were some things off of apple.com I could download/update to make this go more smoothly).