windows and open source software

It seems to me that the ifrastructure supporting open source software has never developed in the windows environment. In the *nix world open source software is highly regarded and accepted. Sourceforge and freshmeat are primary sources for open source software. Distribution repositories routinely accept and distribute open source software. The tools for developing software (compilers, libraries, and ide's) are free and very available (often included in a distro's main selection of software). THe companies involved in the development of software (IBM, NOVEL, RED HAT, HP, SUN, UBUNTU, etc.) encourge people to develop and distribute open source software. None of this exists in the windows environment. Compiles, libraries, and ide's often cost many hundreds of dollars; sourcefore and freshmeat are hardly used, and open source is not trusted or distributed by the main suppliers of software.
I wonder how these different cultures developed and why.