An inexperienced instrument rated private pilot on an IFR flight landed at the wrong airport following a GPS approach to his destination.

Narrative

I called Flight Service for an updated briefing prior to flying. I flew in IMC entering the overcast at 1;700 FT. I stayed in overcast until on top at 3;000 FT. Miami ATC told me to do a visual approach into AVO. I told them I was in heavy IMC and had to do the GPS Runway 5 approach into AVO. They said fine; shoot the approach; radar service is terminated and don't forget to call and cancel your flight plan. They then signed off without giving me any missed approach instructions. I then announced my intentions on the AVO CTAF and heard no responses to my declaring of my intentions on flying the approach; my report at each fix; and on final approach. When I broke out in haze at 800 FT my wife pointed out a runway maybe four to five miles ahead on my nose at 049 degrees heading; the same as my approach to GPS Runway 5 and I flew to that airport. When I landed a civilian fire truck came out to greet me. I told him that I was looking for AVO and was flying a GPS approach and broke out at 800 FT and thought it was that airport. He told me this happens quite often. I then took off for AVO and landed there without incident. I was so concerned about this that I called my flight instructor this morning and told him what happened. He had given me a complete instrument proficiency review the previous month. We are going to get together and review the entire flight and try to re-create what happened and practice the same approach into AVO. He feels this will prevent this from happening again.