Looks like curl isn't installed, or isn't loaded.
If you're using WAMP, left-click on the icon in your system tray, select 'PHP Settings', then 'PHP extensions' and then look for php_curl. Click it, wait for your server to restart and try again.
If that doesn't solve it, you'll need to check if WAMP has edited the right PHP file. When I last installed WAMP, it made two copies of the file, the one it was editing was not the one that PHP was loading. (There was one in Apache's bin directory and one in PHP's root directory).
Hope that helps you out.
@lakshan: Might be a good idea to wrap the curl_init() call around a function_exists() call, like so:
<?php
if(function_exists('curl_init')) {
// Call curl_init(), setup object etc
} else {
return null;
}
?>