Ya know, most colleges don't let you use a calculator in most math courses later on. Heck, I haven't used a calculator since, like, algebra 2. Sure would be useful in Linear Algebra, though. =(
Might want to check with your teacher/curriculum/school to see which calculators are allowed. I haven't had a class yet that allows a TI-92, and most don't go for TI-89s, either. Heh, only class where I actually got to use a calculator was in economics, and that was only a four-function calculator.