I will guess that is a virtual hosting web server. It is redirecting you to a error 404 (file not found) page. If that is the case, then you will need to send the Host parameter also. Like this:
client.println("GET /test.php HTTP/1.0");
client.println("Host: www.mydomain.com"\r\n);
Replace www.mydomain.com with your domain name. Note the double CR/LF is after the Host now.
edit: This is a thread that should be in networking. I expect we will be moved there.