Try ASA GPS Trainer. Comes on CD for your computer, it’s an interactive tutorial for the GNS 430, KLN 89B, and the GX 50/60. It’s not to bad, I used it for the KLN 89B and it was useful, much better than just the simulator, it takes you through entering flight plans, etc.
I am assuming it is equally useful for the GNS 430.
Paul