Marc:
I have a student who's downloaded the Visual C Gambit package for Windows; the Gambit 4.6.3 compile script calls cl.exe, but this page
http://msdn.microsoft.com/en-us/library/9s7c9wdw%28v=vs.80%29.aspx
(found doing a google search for cl.exe) says that this script is available only on Windows 2000, Windows XP and Windows Server 2003 operating systems.
He's running Windows 7.
He's willing to install MinGW and see how that works on his box, but do you need to update the Visual C compiler version of Gambit?
Brad