If Commit Charge is the total amount of physical memory and virtual memory; how can Commit Charge ever be less than Physical Memory?
For example; I have in System Information in Process Explorer registering 1.8GB for Commit, but 1.9GB for Physical.
I think where you are going astray is that it does not include ALL your memory, only that which composes the virtual address space. You don't say if that 1.9GB physical is Total or available, but there is memory that is not allocated to paging, like for the OS, and other hardware.
Here is my current Process Explorer screenshot (I updated my version since your previous question), and I have limit of 6.2GB of Commit Charge, but 7GB of total memory and swap space. My current readings are similar in nature to yours: 2.4GB of Commit Charge in use, and 3.1GB of total memory.