Pushpinder, as an easier alternative to IIS setup of PHP, try http://badblue.com - free web server for Windows designed for PHP. Only 400K download. Click the help tab, select PHP Wizard, then follow the Wizard. It takes about 45 seconds total.
Only installs to a single folder so easy to remove if needed. But basically the fastest way to get PHP up on XP that I've seen, and compatible with Apache from a PHP programming standpoint - meaning the environment variables are supported like Apache, which IIS won't exactly match...