This almost went through unnoticed. Steve Holden (Python Software Foundation) has worked out a fantastic deal with Sam Ramji and Tom Hanrahan (both leading Open Source guys at Microsoft). Microsoft has given fourteen MSDN Premium subscriptions to Python core developers and PSF members. I'm one of the lucky few. , 
The premium subscription includes licenses and downloads of almost every Microsoft product from MS-DOS 6.22 to Windows 7, all versions of Visual Studio and many more stuff. This is very useful for Python core developers. Every developer with a subscription can finally set up multiple virtual boxes with 32 and 64bit versions of XP, Vista and Windows 7 to test and debug issues. 64bit versions of Windows were hard and costly to come by.
I'll keep my Ubuntu boxes for daily work and I'll still be skeptical about Microsoft's open source politics. However I'm glad that their paradigm towards Open Source is changing into the right direction. Python (more precisely IronPython) is going to become more important to Microsoft. I'll put my subscription into good use.
Thanks to Sam, Tom and Steve!