I know nothing about "western riding" cause i've only ever done recreational riding or cattle work, but I would tell you to pretend that this horse has never been worked with because 1) despite what the seller says, it may not have been worked with and 2) even if the horse has been under saddle, if it is still very green, then the horse has gotten old enough that it may be a real unique challenge to train it. It's my personal experience that if a horse hasn't been worked with, then about the time a horse turns 4-5, they are like bachelors (or bacherloettes) in their 30's - they get set in their ways and you have a harder time getting them to do it your way.
I know that in times past, they wouldn't start training them until they were a little older than what people generally do now, but they were also breaking them a different way and for different purposes. Again, i'd tell you start from scratch, and if you don't like to do that or for whatever reason aren't capable of doing it, find someone really good to do it for you.
Last edited by circleck; 02-04-2009 at 04:34 PM.