Ray - I'd like to add one more note if I may!
The "ADDT Includes" includes an elementary version of doing "Clean Urls" (it is documented in the help files) and it works well, but has serious limitations. It's fine for basic sites, but not when a site gets complex. I like to setup my own Clean URL system, and use URL Rewrites in more complex ways, not relying on the elementary system within "Includes".
Obviously these 2 URL's have very different relative positions, but INCLUDES does a great job of retaining it's original paths with any/all it's included files.
Please keep this in careful consideration if WA decides to develop this extension. It's important for the included files not to lose it's postition, regarless of the URL structure!