We know about a bug in ArtRage that prevents it working correctly with the Lenovo tablets, when using the Airbrush tool or Glitter tool. There will be a patch out soon that will correct that.
However the other tools should work. Check your pressure settings, make sure you're using a colour other than white (you'd be surprised how many people do that...)
If you have gesture helpers or right-click helpers switched on, try switching them off (although there is a known bug in Vista where you'll only get pressure support if you have one or the other of pen-flicks or right-click helpers switched on)
AndyRage's mantra for graphics engine code:
"Sure - how hard can it be?"