Screaming Penguin - Source Does Matter

If Microsoft really is working actively with the PHP developer community to improve PHP support and performance on the Windows platform then that is a great move by MS. (Though technically "Zend" is not exactly the same thing as the "developer community", in the long run it's still good news for PHP on Windows.)

Microsoft and Zend Collaborate to Improve PHP on Windows Server

Personally I would never use Windows without being locked into the platform, such as some artifical requirement to use .Net (which yes DOES mean locked in, dont give me that crap about Mono or writing your own CLR for Solaris, we are talking about server side apps here, if you write it in .Net you are locking yourself into a platform, Windows - though I think Mono is fantastic for desktop widgets and such, you just arent going to realistically run your enterprise server app on anything but Windows if you start from any of the .Net technologies). Though at the same time I do realize that PHP is very popular with the "DIY" website types (and that's a credit to PHP, it's easy to use, easy to host, etc) and most folks starting out are probably using Windows as a development platform. I would just caution the world to try to make things portable, because one day you will graduate from Windows, hopefully. Especially if you are using some open source solution to develop in anyway, which was actually designed for a more robust and secure network operating system than Windows in the first place.