Could not able to run first script

I am new here.
I could not able to run my first script. I am using Windows XP.
First I have installed Apache server httpd-2.2.21-win32-x86-no_ssl.msi . I also installed PHP php-5.3.8-nts-Win32-VC9-x86.msi .
On the Apache Service Monitor I can Start, Stop server.
On the command prompt I got the details such as PHP version, built date,time etc. by executing php -v command.
On the browser I got "It works!" when I typed address http://localhost/
I placed phpinfo.php file in "C:\Program Files\Apache Software Foundation\Apache2.2\htdocs".
My problem is I am getting output code of my PHP file phpinfo.php

The contains of file phpinfo.php
<html>
<body>

<?php
phpinfo();
?>

</body>
</html>

I am getting output as

<html>
<body>

<?php
phpinfo();
?>

</body>
</html>

Please help me!
Thanks in Advance.

Not so simple, unfortunately.
The problem is that apache needs to be told that if a .php is requested, send it to the PHP interpreter. The way to do it is to have a line like "LoadModule php5_module "/your_php_installation_path/php5apache2.dll" in httpd.conf and configure it as a MIME module. Search for tutorials on net if you want to get into that stuff.
However, if you just want to start with PHP as quickly as possibly, then you're better off installing a preconfigured Apache + PHP + mysql stack like XAMPP or WAMP -it'll have everything already configured.

Thanks Karthik Shiraly.
I have downloaded & installed WampServer2.3-beata-x32.exe
Now, I can run my PHP scripts. I am very happy!!!

! I'd no idea WAMP is a secret to happiness.