<?
$files = Array("1" => "quick.pdf",
               "2" => "soley.pdf",
               "3" => "power.pdf",
               "4" => "test.pdf",
               "5" => "test.gif");

$filename = "docs/".$files[$_GET[what]];

header("Content-Type: x-type/subtype");
header("Content-Length: ".filesize($filename));
header("Content-Disposition: attachment; filename=".$files[$_GET[what]]);
readfile($filename);
?>