I've taken one year of Arabic. The first two quarters were with a white girl from Alabama who studied at the AUC. She was great. The last quarter was from a Moroccan, he was not. Point being don't put too much weight into having a native speaker.

I think the Pimsleur audio lessons are nice for Spanish and French, not so much for Arabic. I think the best route (barring immersion study) is to take classes, or do self study with the Al-Kitaab textbook and then take more advanced classes (as my first teacher did).