Linux vs Windows: What do programmers use.

I was woundering if it is a common theme for most "Pro" programmers to use linux. I mean a book called C;Programming I have was written on linux. So which OS is it that programmers or hackers, per say, use?

>>62
lets see
1) most ``real'' programmers are cheap.
2) with 1) being the case, why would i want to pay for msdn when i could use the free stuff?