Dear Sirs,
At last I have been able to solve the problem of dvd writers not recognising blank dvds.
I formatted my computer ,loaded XP3 and even upgraded BIOS but it did not solve the problem. Then I came to know about Windows XP Ultimate (by Johnny). I downloaded the dvd iso image from their site and installed it. This solved the problem in one go. Both my dvds now recognise blank dvds with correct info about blank/usable space etc. I have even burned couple of dvds today and it works perfectly. Though the software is very big it has got several brilliant features added to it.
Thanks to all who tried to help me out. I will certainly inform about any future development.