Newbie: Lowering process priority in registry for ntvdm.exe

Hello all,

Can somebody show me how to make a registry change to lower the process
priority to "LOW" whenever NTVDM.EXE starts? Somewhere I read that a
registry value could be set to "0" to indicate low priority and allow other
programs to run without being rendered sluggish. I am running an old 16-bit
program and the CPU usage for this process is a killer.

Thanks in advance...Carlos