The executables in the linux-guest and windows-guest directories are plugins that can be run via the NRPE agent (or NC_Net or NSClient++ on Windows) and then queried by the mrtg-nrpe.pl script.  They allow you to use the VMware-tools API to query virtual memory and CPU usage from within the guest itself.

The check_vmware.pl script requires the VMware Perl API to be installed, and is a MRTG or Nagios plugin that allows the performance statistics data on the VirtualCentre server to be queried directly to obtain statistics for a VMWare farm, server or guest.  It has a --generate option to generate the MRTG (or Nagios) configuration files required.

Try setting a configfile with the necessary information, then: 
check_vmware.pl --mode=mrtg --guest=guestname --config=configfile --generate
check_vmware.pl --mode=mrtg --cluster=clustername --config=configfile --generate

Example configfile contents:

VI_PASSWORD=fjdkhfjksd
VI_SERVER=vcserver.auckland.ac.nz
VI_USERNAME=myusername
