No sense arguing over which OS is better, they each have their place.
If you want to listen to music while surfing, pop a CD in your Windows machine, if you want to edit a document that you know your neighbor can receive, you use Word ... if you want to do your taxes use Excel ... If you want to develop the 80,000 lines of code necessary to control the attitude of an F-18, Windows is the last OS that a programmer would use ...
That's where Unix comes in ... if I am doing large scale SW development, you will be in the Unix environment. Large scale engineering studies, Unix ... Image processing research, Unix. ... etc.
There are plenty of people that will try to shoehorn their favorite OS into trying to make it do something it is not efficient at just to say "My favorite OS can do that." I happen to think alot of SuSE 9.2, but I wouldn't even bother wasting the time trying to get my TV card running under SuSE when Win2000 configured it for me when I plugged it in! ... and in 2 minutes I was watching Sports Center on my PC.
These OS'es are tools to get the job done ... pick the right tool for the job and you cant loose.
Not to put new flame on this fire.. but You could listen to your tunes, do your excel and do heavy duty development in a Unix environment. OS X.