Many schools offer computer labs where software such as Mathematica is available for use, anytime, for free. mg0stisha, ask your professor if your school has such a facility before buying your own copy.
symbolipoint, Mathematica is just a tool -- an advanced calculator. You might be able use it to solve your homework for you, but it will never spit out a complete answer, with all steps shown, ready to be written down on paper and turned in. Such abuse of the tool will also never help you pass your tests, which, in most schools, comprise the bulk of the students' grades.
Instead, the best use of Mathematica, at least for undergrads, is exploration. As a kid, I remember learning a great deal about math by using my graphing calculator. It was like having a full-time tutor that always gave me the right answer to any problem, and I figured out all kinds of things about complex numbers, Taylor series, etc. by simply playing with them on the calculator.
The end result of education is knowledge, and it doesn't really matter whether that knowledge was obtained solely via pencil and paper, or if newer technology was used as a booster. The irony of your post, symbolipoint, is that PF is itself new educational technology, and I believe it has been tremendously successful.
The amount of "stuff" that college students must learn in just four short years has increased dramatically even in the decade since I graduated -- there's no way that today's students will be able to absorb everything they need to learn if they are handicapped by being forced to abandon all modern educational technology.
- Warren