This probably goes to the Platform SDK team; if so, please forward it.
Please make windows headers compatible with the /Za (disable language extensions) option. This would make writing portable, standards compliant code much easier for those of us who have a mix of portable and Windows-specific files in our projects. Right now, /Za is pretty much useless for those projects, since nothing that includes windows.h will compile with it on.
In particular, this issue bites people frequently moving from VC++ without /Za to GCC: http://www.gnu.org/software/gcc/bugs.html#cxx_rvalbind. VC++ without /Za does not make this check, with /Za it does. If you could make a /Zc option that enables just that check (elided copy-constructor is callable), that would make a big difference.