Should Microsoft bundle open source software?

Phil Haack asked this a couple of weeks ago. Time for a quick thought experiment.

Let's assume we're in a parallel universe where Microsoft had bundled nunit with Visual Studio 2005.

There's been a bit of a buzz about xUnit.net lately. It aims to improve on nunit (although Roy Osherove might disagree).

See where I'm going with this yet?

What would happen if the alt.net, alpha geeks decided that nunit was far too passé and xunit.net was the future?

How does Microsoft handle this?

Do they continue to bundle nunit for compatibility, or do they jump ship to xunit.net and force their customers to migrate? Bundle both and try to educate the customer which to use?

Has xunit.net been released in enough time to get into Visual Studio 2008? If not, when and how do they release it?

What needs to happen for their international customers?

Who do Microsoft's customers call when they have a problem with xunit.net? How do patches get distributed to Visual Studio customers?

Or would they use a framework over which they had control?