checking for app's

How to write code to continuously check IF a program is running?
I want to do an action in MY program, when e.g. Microsoft Word is launched by the user of that computer.

i think it might work if you use the findwindow api and looped, searching for the caption then checking to see if it find the window you want. i think word has to default startup caption of 'Microsoft Word'.
check out:
http://www.mentalis.org/apilist/FindWindow.shtml
or
http://www.mentalis.org/apilist/FindWindowEx.shtml