Some distributions do have big companies behind them, look at Ubuntu - Canonical Ltd (
http://www.canonical.com/aboutus)
That's why Ubuntu is evolving so quickly, every six months we see great improvements with each new release.
Now for the first time ever (that I know of) one of the worlds largest, if not the largest computer systems company, Dell are offering a Linux distribution (Ubuntu) pre-installed on some of their machines. That is a huge step for Linux and shows how far it has come.
I don't know when you last used Linux, priteshvarsani, but there are more applications available than on any other OS.
I think the problem is (no offence) people like yourself who may have used Linux in the past and either didn't think much of it or had a bad experience, so then that puts you off and you tell your friends how difficult it was to use and how nothing worked and they tell theirs, etc. etc. 6 Months later (or sooner) the problem you experienced may have been fixed, but you've given up on Linux and don't know that 6 months in a Linux life cycle is a fairly long time and much has changed.
The reason MS has such a big market share is simply down to pre-installing.
You buy a pc, up until recently you didn't even get a choice as to what came on it, it was usually the latest Windows version. That automatically means MS has the market and software developers have to make their application compatible with Windows.
I'm not saying that Windows is crap, it is fairly easy to use and works but it comes at a cost - cost of software, cost of support, cost of upgrading your machine to use the latest Windows version, cost of paying some tech to fix your pc after it became virus ridden (not everyone is technically minded) etc.
Linux offers a much cheaper alternative, that is (usually) more stable than Windows, viruses, spyware and malware do not affect it and it's free.
The way to get it into mainstream is to talk about it more. I'm trying to get my dad to try it at the moment as I'm about to upgrade his machine, so he'll be reinstalling his OS anyway but he's scared of the unknown. He's not very technically minded and isn't in any kind of IT loop, so the first he heard of Linux was through me. If he could walk into PC World and see machines offered with Windows OR Linux and see free Linux CD's and books on Linux etc. then he would feel more at ease. He is one of those people with the mindset that you get what you pay for, so how can anything free be any good?