Hey,
I couldn't install Forge with the windows installer, so I asked google about it. I found a solution that helped most of the people:
http://www.minecraftforge.net/forum/topic/52285-forge-installation-issues/?do=findComment&comment=255402
If I open up the command prompt and type the command in i get the error message: Mainclass .net.preferIPv4Stack=true could not be found or loaded.
Can anyone tell me how to fix this?
PS: I renamed the installer to forge.jar, just so u dont wonder.