getting a string from an external asp file

This has probably been answered somewhere else, but I'm bashing my head against a wall trying to find the answer. I'm trying to call an external ASP file from a different server (for e-commerce authorisation) and send POST data to it. The ASP will return only a string (ie prints it!!) and I need to get this into a variable so I can process it. I assume I can't use a FORM for this as the ASP doesn't return HTML data. I've tried EXEC, but to no avail and need some help here. Thanks in advance.