MY computer went bananas! B-A-N-A-N-A-S... Help!

So last night before going to bed I put the Tiger Install DVD and left it installing, this morning I woke up to a blue screen and a circle with dashes going in circles (like it was searching) I went to bed for 8 hours by the way! So it's not speaking much for my computer... Then I tried to reboot several times but then it stayed on the white apple screen with that same circle dashy thing. Then I booted up pressing Option, and tried to go into the DVD and then go to Startup Disk and then to OS 9. So then it's opening up and it prompts me saying that my comp. was improperly shut down, First Aid Disk is going to repair and check for any problems. Then that is done and it proceeds to open up. IT gets to that lovely gray screen with the wonderful white dancing lines on it, I see the time but then it fails to open the entire desktop. Then! All of a sudden the screen goes blue, then white and it says "Welcome! Bienvenue!" And it is acting like I have a brand spanking new computer?! What the heck! Then it makes me register as if I was doing it for the first time, so I fall for it and then it tells me to setup my internet, so I do it, out of force of course... Then it tells me to connect, so I did that and now... it went to a blue square in a gray screen. And now it is opening in OS 9... I wonder if my OS X will be okay? I doubt it, I have no luck... And I wonder if I can log into OS X... I saw that in the Startup Disk, that my Mac HD OS X was now 10.4 instead of 10.2.8... Anyone know what the heck happened???? Last night I clicked "Upgrade" and now I have a feeling it did more than that...