My TFT is mounted fairly low down too, and I've got tinted windows which makes it a bit harder to see. I've never had a break-in, and hopefully never will.
My security...
1) Locked in garage overnight
2) Clifford Concept 300 alarm / immobilser
3) CCTV on the garage and around the house (24/7 recorded)
4) Flood lighting
5) Nosey neighbours!
6) At work, it's in a secure underground (private) car park... with CCTV
7) I never leave it anywhere out of site if I can help it.
8) Rhodeshan Ridgeback!
Also, I firmly believe that if your TFT looks factory then it'll look like it's meant to be there and theives are too dumb to think carputer!