R - The open source alternative
Commercial software can be prohibitively expensive. Therefore, we strongly encourage you to try the open source statistical programming language R which runs on both Windows and Mac. You can use R like MATLAB, or you can try a myriad of preprogrammed packages for R that perform many of the same statistical procedures that are found in commercial statistical packages. There is a learning curve for R, but once you successfully master the R language you will never have to rely on obtaining an expensive commercial software license. There are volumes of helpful R resources but here are several to get you started:
The R website
A Quick and (Very) Dirty Intro to Doing Your Statistics in R
R for MATLAB users