I made a test on my Express edition on the "FullScreen" value, but I
don't have a "Build Time" one.

Do you have a "FullScreen" key ?

can you run this in a shell, to see what value you get for FullScreen, 
and for build time ? (I find it strange that this one has a space btw, I
couldn't find a key with a space on my side)

>>> from distutils.msvc9compiler import Reg
>>> path = r'Software\Microsoft\VisualStudio\9.0'
>>> Reg.get_value(path, u"fullscreen")
>>> Reg.get_value(path, u"build timing")

If you get a value for fullscreen, we can have the same test for VC9 and
VCExpress.