Zend question

I'm about to set up a new vbseo install for a client on a Rackspace server.

I uploaded test.php to see whether to install the Zend or Ioncube version - but it came up with a no for both.

I asked Rackspace if they could install Zend, but they replied that the server is running PHP 5.1.6 which comes with the Zend engine installed.

Question is, will vbseo work under this sort of environment?

Because it's a client site I'm not able to test if it breaks or not with the wrong install.

What is the URL to the test.php on that server? (You can PM it if you like.)