What graphing calculator should i get?

I've never used or owned any graphing calculator before. i will be taking College Algebra this semester, probably followed by Calculus. i don't mind paying more for a better calculator if it will be allowed on the test. what I'm interested in is the TI-Nspire and the TI-Nspire CAS. i don't even know what CAS is, but if i need it I'll get it. I notice that the Nspires are between 140 and 160$, which isn't much higher then the other TI models. does that mean that it is not as good in some respect? Also, should i consider some of the HP or Casio calculators? once again, price isn't so much the issue, i just don't want to have to buy another calculator next year. thanx in advance. oh, and my college algebra course requires a TI-83 or higher.