Windows 7 Activating a program when files in a folder change?

I would like to watch a certain folder and run a program ASAP when it receives any new files. It would seem to me that a service is the logical alert mechanism, but there doesn't seem to be an option in creating a service to trigger a program on that event. The program triggered can most easily be a batch file, but if it were an .exe, I could probably handle that.

The best I've been able to do so far is a service that triggers a batch file every few minutes to look at the folder and do whatever, but this creates an annoying flash on my screen every time it runs. I suppose it is quite inefficient as well, because I expect the event to be rare. But when it happens, a response should ideally occur within a few seconds.

I'm sure the ability exists in Windows somehow, because I have software that can do this for its own purposes (in fact, it can watch hundreds of folders, not just one).

Any suggestions?