We currently offer a massive range of downloads for FSX, as well as older flight simulator add-ons for the ever-popular FS2004, FS2002, CFS3 and now becoming ever popular with dediced virtual aviators is Laminar Research's X-Plane series.
Yes, you can load your flight plan using the Flight Planner and then it will show up on your GPS.
To save a flight plan
In the Flight Planner, click Save.
Note: The Save button is dimmed until you create a flight plan.
In the Save Flight Plan dialog box, use the suggested name for your file
Type a new name in the File name text box.
To load a saved flight plan
In the Flight Planner, click Load.
When the Load Flight Plan dialog box appears, select a saved flight plan.
Click Open to load the file.
All this and more is in The Learning Center with in FS.