I'm pretty sure Windows 2000 has a 'cron'-type of facility (scheduled task, or whatever it is called), to have the OS call your script periodically. With a little modification you could have your script do the probing and terminate within 60 seconds, and have the OS startup an new script every 60 seconds.
From your last description it sounds like you run your stuff from a terminal window. It should also be possible to run it as a service/in the background so it is not dependant on somebody/something terminating your terminal window. This doesn't exclude something/somebody terminating your script itself ofcourse.
Also, for network performance/failure type of measurements there are some excellent pieces of software available (written in perl):