DO NOT GO TO THAI PASSION - it is easily the worst thai place in North America.
Thai Village is good, but for some reason, their Pad Thai is not so great. However, they have Nur Lard Nar which is my favorite THai dish in Austin if you get it really spicy. Also, Tiger Cry is really good there. They also have the best Tom Ka soup I have ever had. And its pretty cheap.
Head to Bangkok Cuisine which is up on Burnet road right by the 183 intersection.
I have spent quite a while in Thailand & these guys know their stuff.
Very very good & very reasonable prices.
The Green Curry, & Penang Curry are my favourites, along with the Tom Ka soup. YUM!