One of the many useful tools that comes with the XP Support Tools is a utility called TaskKill. TaskKill lets you dump a process that refuses to let you kill it from the Task Manager. On occasion, I have run into processes that would throw an "Access is denied" error when I try to kill it from the Task Manager. Once you have installed the XP Support Tools and have it as part of your path, simply type taskkill /? to get more information.