Try this one, Qwertick. It's portable, doesn't need to be installed anywhere, just extract the tiny exe file from the zip to anywhere on your drive, and double-click to run it when you start typing. Tested in Word 2007---Win7. (I've used a couple of Nattyware utilities, like Pixie, but not this one)
http://www.nattyware.com/products.php
Hope it does what you want.