Apparently, as per Commit charge is 100% full but physical memory is just 60% when using no page file and http://brandonlive.com/2010/02/21/measuring-memory-usage-in-windows-7/, the Commit numbers in Windows 7 Windows Task Manager include both the physical and the swap memory, and count the virtual memory that has been allocated, but not necessarily has ever been used yet (i.e. not necessarily backed up by any physical source).
As such, is there a way to know the actual swap usage on the system? Simply subtracting physical memory from the Commit numbers won't work, as it apparently includes this unused-but-allocated space, too.
I mean, Windows 7 is supposedly a modern operating system; surely it must have the functionality to see how much of the swap space is actually presently being utilised, right?