I recently came to know, that with Parallels Desktop and Server, you can use the command line utility "prlctl". I have recently created a shell extension for my Alfred like below
#!/bin/sh
/usr/bin/prlctl suspend "Windows XP"
exit;
to resume, just replace suspend with resume in above script.
And then assign this extension to hotkey. So with simple global hotkey I can resume or suspend the VM. And also, can call the shell script from anywhere.