MotoH is absolutely right.
When I was looking to buy a calculator, I was torn between and HP 50G and the TI-89 Titanium. A friend of mine who is getting his masters degree in mechanical engineering told me that I should, without a doubt, go with the TI-89. He said given that TI's are pretty much the standard calculator used in academia, you'll have no trouble finding help from teachers or students when you need it. Not so with HP's.