Use PHP curl.
PHP doesn't come with curl by default so you need to enable the php_curl extension in your php.ini file.
If you're running IIS, you'll also need to copy the libeay32.dll and ssleay32.dll libraries to the C:\Windows\System32 folder (these dll's are included with the php package that you extract)
http://us3.php.net/manual/en/function.curl-setopt.php
Here's a quick example... this will provide you with the header info for google.com
<?php
// create a new cURL resource
$ch = curl_init();
// set URL and other appropriate options
curl_setopt($ch, CURLOPT_URL, "http://www.goole.com/");
curl_setopt($ch, CURLOPT_HEADER, 1);
// grab URL and pass it to the browser
curl_exec($ch);
// close cURL resource, and free up system resources
curl_close($ch);
?>