Honestly, this is a much better solution than using the HTML catalog:
http://www.safetynetweb.com/Dynamic-Search-Engine-Friendly-URLs-pr-1.html
If you would rather use the catalog, here are some suggestions:
1. Generate the catalog in the root directory. Re-directing customers and search engines to the catalog is just not good practice.
2. Make sure you block the search engine spiders from indexing .php pages if you are going to use the catalog. If you don't, you will get penalized for duplicate content.