Killing A Process Safely...
Anyone who has ever done any real scripting in Windows knows there are about a million different ways to kill a process.
However, be it VBScript or PowerShell there is only really one "safe" way (not including heavily complicated .Net calls in PS):
taskkill /t /pid <pid>
A couple of quick details. /t tell it to "treekill", or in other words kill all child processes as well (which is pretty crucial when killing virtual apps as their child processes hold the virtual environment open).
/pid is pretty self explanatory, you can find a processes PID pretty easily:
$proc = Get-Process -ProcessName WINWORD$proc.ID
taskkill /t /pid 344