What!?
You shouldn't need to touch the registry!!
I assume you either dom't have a webserver running on your machine or, if you do, it's not set up correctly.
If the first is true, get apache.
if the later is true.... read on!
- open your httpd.conf file
- search for the string AddType
- Insert this text with all the other "AddTypes".
AddType application/x-httpd-php .php
Note: If you save your scripts as anything other than .php then change that part to suit you.
Save the file
Restart Apache
Thank god you didn't play with the registry