I lived in Texas for 4 years and they let me take the class with a New Mexico license

Living in TX as a student or as a non-permanent resident? Otherwise you have six months to get a TX license. or they ticket you for that, too...
The main advantage to defensive driving is that the points don't go on your license and your insurance company doesn't hear about the ticket. Other than that, it can cost almost 2x the price of the ticket because they charge you for the course and "court costs" plus the fine itself. At least they did that last time I went, which was ages ago... *knock on wood*