Thanks for the tapping advice. Otherwise I would lose my data..
I have just verified that the technique worked for my 80gig even when BIOS screen was up. In the first try, IDE auto detection was failing. Tapped once and retried the detection, and the drive was detected after a 'tock' sound from the disk. All parameters popped up, saved and exited bios..
It's booting now.. Thanks a lot..
(This is my first post)