Over the last week or so I have mentioned a couple of interesting command-line parameters that can be used with Virtual PC.  If you want to utilize these options but not have to worry about users using the correct shortcut / parameter - it is possible to override the command-line parameters by adding them to the VMC file.  The following chunk of XML will always enable the 'disableclose' option (discussed here) if you add it to the end of the VMC file (just before </preferences>):

      <disable_close type="boolean">true</disable_close>

Note that this approach is only viable for a subset of the command-line parameters under Virtual PC - as a number of them need to be specified at application launch, rather than at virtual machine launch time.