Thanks Shadow,
that was really a long and well thought answer. Well as for me, I am ancient (my year of birth is displayed) but unlike other ancients I am working with computers right form 1966 !! There was no display, no keyboard no high level language. Those were huge monsters with patch chords 8-bit word size, absurdly low memory (using valve modules for each bit !!) producing unthinkable amount of heat. Then I was graduated to PC's working on DOS and then workstations working on Unix and Berkley. Being a mechanical design engineer had to use a lot of finite element analysis and CAD software. Also had to write own programs in C and Fortran - no graphic interface.
In the process when I started to use Windows based PC's I did not have enough organic memory empty in my brain and didn't have the time to go in depth into the labyrinths of Windows registry.
I welcome suggestions regarding purchase of a dependable registry cleaner + compactor. I understand the importance of keeping it clean.
Thanks and regards -
Ranabir