I need to listen to everything that goes (both directions) through a virtual serial port on Windows 7 64bit.
I do not need to send anything, just monitor the communication for debugging purposes.
How can I do that?
Old question but still actual. There are many applications that can monitor serial port. But only several are supported on Win7 x64, Win8. I also faced this problem. And i founded a good soft - Eltima serial port monitor works on Win7 x64.
You can use Process Monitor  from sysinternals (now bought by Microsoft).
It allows to see all reads and writes made by a process.