I have had SBS for about four years..........best value item ever bought...HOWEVER if you dont want to shell out 500 quid , then for just £25 ( One off fee ) you can join the Planeplotter network and get full european coverage , in near real time.
PlanePlotter from COAA
In addition , planeplotter now has a facility which allows the approximate location of non plotting a/c to be determined......full swqk naratives plus two stage SSR code history.
For an idea of coverage , have a look at my website
The SATCOM satellite consultancy and click the "Marathon" button to see a still frame of PP in action.
There's also a flow animation here :
http://i42.tinypic.com/35irmuq.gif
Individual SBS is limited by your line of site , Planeplotter isn't , but does depend on SBS users ( and radar box users ) to input their data.
Planeplotter has full user support via a Yahoo group.
Brilliant all round product.
John