Jeremy is correct.

To further clarify, *all* 2.7 Windows builders *are* using VS 2008's compiler toolchain, but they're using VS 2015's MSBuild with VS 2010's description of 2008's compiler toolchain to build the projects described in PCbuild/.  It's a mess, but it works and makes things much easier to customize.  The two specific VS9.0 builders are using VS 2008 directly via the PC/VS9.0 build files, but ideally the output from both methods should be exactly the same.  As Jeremy pointed out, the PC/VS9.0 files are still explicitly supported, and those two builders were set up to make sure they're not broken.

Anything older than PC/VS9.0 is explicitly *un*supported, and I would have no problem with just removing them (and any support for them in sysconfig).