Statistical packages available out there as freeware or open source software.

• PAST. This is probably the easiest to use statistical package out there, and it is geared especially for paleontologists (as you might guess by the name, which is short for "PALaeontological STatistics"). You can run diversity indices, PCA, and a whole bunch of other methods.
• R. The gold standard in statistical analysis--this is for people who are really serious about their data. One big plus with R is that it handles large data files without batting an eye - this was a lifesaver when I had FEM outputs with over 150,000 values (to be fair, PAST loaded this too, although much more slowly and only with a lot of data massaging. SPSS choked.)! R has a very active development community, and you can find packages to do just about anything. .
• (S)MATR. This handy little program, available as a standalone executable for Windows (also running under WINE in Linux), an R package, or a MATLAB toolbox, will fill all of your reduced major axis regression needs.

Dear Ajit Kumar!

Thank you very much for such a full answer. It will help me a great deal!

Check this paper out:

What's Better—R, SAS ® , SPSS ® , or Stata ® ? Thoughts Instructors of Statistics and Research Methods Courses

Thank you very much.