Finally I did it !!! After a lot of hectic job I am able to remove Microsoft Vista from my system. Oh pretty pathetic, I almost tried almost all the combination with vista. Vista- Solaris, Solaris-Vista, Vista-XP, Vista-Linux. At last I get rid of that buggy UI and I am able to install my VPN. Don't know what happened to these big companies like HP or Dell. "We recommend vista for this notebook", who the hell you are to recommend me that which OS i will install and which I will not. From last 3 days I was struggling for drivers. But now the laptop is in OK condition at least I can listen music, do some basic work. Still I am struggling for some drivers.
Thanks to all my office-mates who helped me so much.