Page requests for foo.php would need to go to foo.aspx, ditto foo1.htm to foo1.aspx.
I supppose I could develop a comprehensive URL re-writing mechanism. Another alternative (it's not a large site) would be to create static PHP and HTML pages for each page on the old site and map them to their countertparts on the new site. Just wondering if anyone else has tackled this sort of problem before. Don't want to loose the search engine and other external link traffic. Lot of info on teh web about how to go from asp to php. Hmmm ...