force .html files to be executed as .php

[misson]

As for using a rewrite - I didn't want to do this b/c I thought that it would create a duplicate content violation for search engines. That is if I have Page X linking to mydomain.com/index.html and another page linking to mydomain.com, both would return the same content. Wouldn't that be considered duplicate content?

Possibly; I'd need to look into it. I suspect (given how pervasive "index.*" is as a default directory index) that search spiders would consider the two URLs to be equivalent. If you're really worried, you can have your rewrite rule send an external redirect, forcing the index file name to be included in the URL. Once all pages have been converted, remove the external redirect.