RE: Whats a trainer?
On the topic of simulators...
FMS is pretty good value for money because it is free. It does not have all the realism you might get for $$$ but it gives the point-of-view, or orientation, that seems to be a major challenge to a beginner.
I did not get the Alpha 8.5 version to run on my new XP PC but the older Beta 7 seems to be equally at home on my XP as it was on 98SE.