Re: open source software for CART and Principal Component Analysis

                              Hello Leo,
you might to take a look at R (http://www.r-project.org/):

  R is a language and environment for statistical computing and
  graphics. It is a GNU project which is similar to the S language and
  environment which was developed at Bell Laboratories (formerly AT&T,
  now Lucent Technologies) by John Chambers and colleagues. R can be
  considered as a different implementation of S. There are some
  important differences, but much code written for S runs unaltered
  under R.

I have not used it myself, but it does appear to support PCA (I don't
know about CART).
                                regards
                                    Roland