64-bit Windows on AMD64/Intel EM64T is somewhat supported in the 7.0
release.  A collector can be built with Microsoft Visual C++ 2005.
The resulting test programs have been known to work at least once.
More testing would clearly be helpful.

Currently only NT_X64_STATIC_THREADS_MAKEFILE has been used in
this environment.  Copy this file to MAKEFILE, and then type "nmake"
in a Visual C++ command line window to build the static library
and the usual test programs.  To verify that the colllector is
at least somewhat functional, run gctest.exe.  This should create
gctest.exe.log after a few seconds.

This process is completely analogous to NT_STATIC_THREADS_MAKEFILE
for the 32-bit version.

Note that currently a few warnings are still generated by default,
and a number of others have been explicitly turned off in the makefile.