The Flight Sim store is definitely the way to go.
I have recently purchased Microsoft Flightsim X with add on photo realistic scenery. Unfortunately, I haven't been able to use the add o scenery yet as my computer isn't powerful enough.
Heaps of fun doing a variety of missions. Over 24000 airports worldwide, most nav aids in Aus if you are using it for IFR proficiency. One of the missions gave me an AH failure at night in a Kingair in IMC, glad I was on the ground as I completely messed it up
Make sure you purchase a control column with throttle quadrant. Too hard to control the aircraft using the keyboard only.
cheers
Omega