I have a recent (late 2011) macbook air with HD Graphics 3000 and driver 188.8.131.529. My laptop connects to monitors and tv's just fine, but it never works with projectors when I'm running Windows 7. It does not even detect the projector regardless of how I plug in the vga cable to the miniport. It does work when i'm running the Mac OS.
This is critical as I only use Windows 7 and need to present a lot.
Are you dual-booting Windows 7 and Mac OS X via BootCamp? If so, you might want to consider Fusion or Parallels. They each cost between $30 and $40, but this would fix your problem without much hassle. I know Fusion allows you to port your BootCamp partition over pretty seamlessly, and I'm guessing Parallels might have that too.