It doesn't seem to be possible to convert VHD files from Microsoft Virtual PC to VMC format from the same program. Simply not possible. You can only convert whole virtual machines into other formats, not just few files.
Convert Virtual Hard Disk to Microsoft Virtual PC settings.
We found one software available in the database for this conversion.
Microsoft Windows software - convert vhd to vmc on Windows
A application used to run virtual computers on one workstation
Convert from vhd file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.