Using VNC to connect to a Mac (10.7.5) from Windows
I stumbled on Vine Server 4.01 by Eggplant, which solves this problem completely and is available at www2.tesplant.com (The earlier versions apparently cause trouble for 10.7+).  Note this is not the version available on sourceforge.

Vine Server 4.01 worked immediately on my Mac and automatically selected an port to use for VNC connections, something which had been baffling me before I found the Vine Server software.  I could then include this port with my Mac IP address when I used TightVNC on my Windows 7 laptop, and was able to connect remotely to the Mac with (almost) no trouble:  The only hitch was that first I needed to set a VNC password in Vine Server, which you have the option to do upon launching the server.  (No need to set a VNC password through System Properties->Sharing, so all the choices are centralized in the Vine Server interface.)