After downloading mingw-w64, I didn't know what to do with it. I am using a Cygwin environment; first I tried putting it under /usr/local, but it couldn't find any of its own includes.
Brian Hawley's thread was a big help, and I reinstalled to c:/mingw, edited my .bashrc to have /cygdrive/c/mingw/bin, and then edited my makefile to explicitly call x86_64-pc-mingw32-gcc.exe.
Now it...
2009-02-07 21:21:21 UTC in MinGW-w64 - for 32 and 64 bit Windows