I was about to say POE until I read the win32 part. I think it's meant to work under win32, but I'd guess there exist problems with it.

What don't you like about the while/sleep loop? It seems fine to me really. Are there problems with sleep in win32?

If nothing else, sleep for 1 or 2 seconds and just check the time with localtime and compare it against a $last_run variable or something like that.