Not me! I was a Linux/Beowulf cluster partisan when I was a grad student. I've got a Debian box and a Mac box at home. And I answered questions for the GPL FAQ mailing list for years.
But, I'm working on a team which is trying to solve some problems that I think will never be solved by the Open Source community, because they are 1) hard, 2) not sexy, 3) involve a lot of scut work, and 4) benefit from the fact that MS owns the operating system and the development tool stack and the collaboration layer on top of it. There are times when being a monolith has its advantages. Plus, it's in an area where *nix has a 95% market share, so the team I'm on can't afford to blithely ignore customers' needs. Competition really does focus the mind.
-- John
-- "The more I practice, the luckier I get." -- Ben Hogan