php 5.3 will no install as an isapi module only as a CGI module. If you are following Our web Development Before you begin tutorial, you should not use 5.3. You should use 5.2 instead.
See the following note on page 5:
Download the PHP 5.2.10 zip file at downloads.php
Note: These instructions only work for PHP version 5.2. PHP 5.3.0 requires different instructions that are not covered in this document.