I agree with Mark. A cat5 cable is preferable.
Remote console extenders are an easy way to have a hardware based remote control for your PC in the observatory. eg:
http://www.aten.com/KVM-Extender.htm
You plug a monitor, mouse and keyboard in the house and a long cat5 to the observatory PC with its own monitor, mouse and keyboard. This is a common approach in IT server mangement and industrial applications. Primitive but effective.
I still stick to the old reliable serial connection for controlling my PME. Software Bisque also recommends steering clear of wireless in this situation.
guy