TCP/IP client says CONNECTION REFUSED!

telnet is not recognized as an internal or external command, operable programme or batch file

Windows 7? (probably 8 too, but I don't have that) If so, you can install the telnet client, that MS thoughtfully decided you wouldn't need, by going through Control Panel/Programs and Features/Turn Windows features on or off.

We've been 'upgraded' to Windows 7 at work.