I'm in the same category as dobebug - old, experienced, and wondering what you have that is so valuable that you feel the need to use another life as the deterrent for possible theft. A surveillance camera system costs a lot less, and an alarm system that ties into the police 911 line also is less expensive, needs much less upkeep - no walks, no training, no food or vet bills, etc. Plus - God forbid - the heartbreak (and guilt) if your dog is injured or killed by some punk.
Our dogs (Dobes, German Shepherds, Boxers, German Shorthair, and a terrier-poodle mutt) have ALL been very protective and excellent deterrents - but not because we trained them to... simply because they loved and respected us and wanted to protect us, and their territory. It's something they do out of love and a sense of duty. So far, except for a couple of times back in New York, where the burglars were obviously watching and broke in at exactly the times when we were out walking the dogs, any attempts have been thwarted by our dogs - evidenced by screens pushed OUT of windows, with happy dogs sitting in the windows waiting for us to return.
If you seriously want estate-type guardians, you need more than one (they work better in teams) - get mastiff types or a Bouvier or Giant Schnauzer, a Malinois or Kuvasz, or a Rhodesian. But as has been said - they still need 3 years to grow up, mature, be trained, and there's really no guarantee they'll have the temperament you're wanting. Don't flaunt your "stuff", be low key and discreet, and when you do go out, make sure everything is locked up tight. Get an alarm system if you have such expensive items - to protect your dogs from harm, as much as to protect your "stuff"! Your dogs, like kids, should be much more important.