This might not be appropriate for your situation, but I have found it surprisingly easy to build emacs from git by using MinGW/MSYS. If you need the exact command line, send me email or reply here and I'll post it when I get back to the office on Monday.
The only non-trivial steps I had to take were to track down the "dev" msys packages for jpeg, png and xpm libraries. I do not link my nightly builds against gnutls, just to set expectations [my experience with non-native security stuff on windows leads me to avoid that headache; YMMV].
