PowerShell: test connection in as few characters as possible
PowerShell v2+, 63 bytes

You can use a different constructor to create the object and connect in one go.

(new-object Net.Sockets.TcpClient('192.168.5.5',445)).Connected


I've verified this works in v2 on my Windows 8.1 machine. That constructor is supported by .NET 2.0, so this should be v2 compatible.