Clean install problem!!!

Ok, my son's computer start failing to open IE; I tryed fixing to no avail. We decided to make a fresh install (with a "new" 80 Gigs HDD) and everything falls in place ... until I hooked up the other HDD, a 120 Gigs. And here is the problem, the computer locks up, looks like is looking for something but fails to boot. Is not recogniced either if I use an external housing. Since we still have the old 40 Gigs, I put it back and inmediately the 120 is recogniced! Am I doing something wrong that I Am overlooking??? I checked and made the adjustments in the BIOS.

This is one 2.53 Mhz., XpPro, ASRock Motherboard, 512 MB RAM, ATI Videocard, Live 24 bits Sound Card, Modem. Any ligth will be apreciated!!!

 

Do you have the correct Master/Slave heirachy?

Are the drives detected and displayed correctly in the Bios?

 

Agreed check the the jumpers on the back of harddrives

 

Yes, checked them again (eventhough I just put the jumpers as in the old HDD) and I had it in Cable select, so changed to Master and the other one leave it as slave and this time the comp. booted, when I checked over to disk management first showed with errors and at risk?, right clicked and said add to your... I did and now appears healthy and as a simple volume. Now I wonder if there is something additional that I have to take care of that. I already defragged and virus scan.

thanks for your time, I learned something with this and in addition thanks for any additional info. This is a great site!!!