Well, I want it to be supported on such systems.  So this is a good test.  I wonder if it's an issue with Windows XP.  For instance, I bet if I setup the new build environment in Windows XP, it would be forward compatible with Win7 and Win8, but not the other way around (it's being built on Win7-64bit right now, but as a 32-bit app).

I assume your Windows XP system is 32-bit... correct?