I had been testing "MS Virtual PC 2007" and "VirtualBox", and it turns out that "VirtualBox" have the problem serial data is comming out of the VM, no problem, but no data is getting in.
"MS Virtual PC 2007" is working ok, data in and out nicely without any problem.
It is strange that a so native thing as the serial ports do not work in a DOS VM.
When I install a Windows (98/XP) in any of "Vmware Workstation", "MS Virtual PC 2007" or "VirtualBox" the serial ports is working as expected.