gringorocks,
   Having the Garmin 500 is a nice add-on and helpful in learning.  Here is what I did:

To those of you who are struggling with the Trimble here is an easy solution that works for me. You CAN install the Garmin 500 GPS to view in a window alongside the Trimble ..... and then you can upload what's in the Garmin to the Trimble so that both have the flight plan loaded. This is especially helpful in multiplayer flights where you can't take the time to re-program the Trimble. You can resize the Garmin 500, see BOTH units, and it's a great aid in learning ILS approaches. Here's how I did it.

Google up the free application called "GPS ANYWHERE" and install it to the Cheyenne, which is NOT going to work until you modify the file called "panel.cfg" in each of the 4 different Cheyenne aircraft series. In order to see the small portion that you will insert, install GPS ANYWHERE to a different aircraft that does NOT have a GPS, and then inspect it's panel.cfg with Notepad and take notice of the section that contains the GPS 500 instructions, copy them, and then REPLACE one of the least used Windows in the Cheyenne's panel.cfg. I use [Windows03] in the Cheyenne (shift-4) as it's one of the least used for me.

Now, when you are in the Cheyenne and want to load up a Flight Plan, bring up the Garmin 500 (shift-4), enter your destination airport by using the Direct-To, and then select "Aux" on the Trimble and import. You now will have a flight plan from where you are to your destination airport and you can see both GPS units on the dash, AND if you resize the Garmin it will fit nicely on the far left away from the instrument panel. I changed to Garmin's initial display size from .5 to .3 in the same instructions we pasted in, so when it displays it does not cover such a large area.

Having Your Garmin "backup" display up will show if you are on the right ILS path and in line with the localizer beam and is helpful to visually show if you are doing the procedures correctly. Not for the purist .... but for those of us who are still learning.

Change the window size and position of the GPS by modifying size and position in the panel.cfg
Size=0.3 is about half the original and position=6 is lower left hand corner.  The upper left hand corner would be 0 and the bottom right hand corner would be 8.

[Window03]
size_mm=456,378
window_size=0.3
position=6
BACKGROUND_COLOR=0,0,0
VISIBLE=0
ident=GPS_PANEL
gauge00=fs9gps!gps_500,0,0

pm me if you have any ?s.