As one famous game industry developer said recently in my connect bug:

This is not a sane decision.  Any real-world app developer, armed with this information, will pin their development tools to Visual Studio 2010 for the next five to ten years at least.

We can't afford to alienate our customers by breaking our product on XP.  So we'll be skipping 2011 until Microsoft figures this one out.                                       

I suggest you vote on the issue (both pro and con) at both:

http://connect.microsoft.com/VisualStudio/feedback/details/690617

and

http://visualstudio.uservoice.com/forums/121579-visual-studio/suggestions/2287078-allow-mfc-11-to-run-in-xp-sp3

Ted.