Ric,
I run a Celestron CG5 and a Meade DSI from 20 metres away inside my house. You just need the 4 pin phone cable with the right DB connectors (else get a crimping tool and a $10 multimeter and a DB to serial convertor) and a couple of 5m USB extenders with repeaters built in and daisy chain these into a powered hub. Run the wire through PVC piping to keep it water proof and your done.
The benefit of this is that desktop PCs are generally $ for $ more powerful and reliable then laptop PCs. You can put very large screen monitors and / LCDs and many power hungry devices into a PC. Its more comfortable inside sitting at a desk in a leather chair with a heater on...
PCs are vastly easier to upgrade, customise or service than laptops. Throw in a dual core CPU (or a prorgrammable 7th generation GPU 0 read General Purpose GPU processing at say Beyond3D, given a high end GPU has around 24 times the image and floating point grunt of the largest CPU and I think Photoshop facilitate using this otherwise dormant processing power).
http://www.gpgpu.org/
Also PC hard drives are alot faster (lower seek times, much faster platter rotational speed and higher sustained data transfer speeds) than laptop drives.
Consider all your options before you spend. The best places I have found for custom PC parts or (finished products) is
www.fluidtek.com.au and
www.auspcmarkets.com.au . Also keep an eye out for Dell offers too, sometimes they surprise and the build quality is excellent.