I encountered the R Language recently with O'Reilly books and while from the context I knew it was a language for dealing with statistics, doing a web search for the support web site was futile. However I have now located the web site and it is at http://www.r-project.org/
R is a free language available for a number of platforms including windows. CRAN mirrors are available at a number of locations worldwide.
Here is the official description:
"R is a language and environment for
statistical computing and graphics. It is a GNU
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.
R provides a wide variety of statistical (linear and nonlinear
modelling, classical statistical tests, time-series analysis,
classification, clustering, ...) and graphical techniques, and is
highly extensible. The S language is often the vehicle of choice for
research in statistical methodology, and R provides an Open Source
route to participation in that activity.
One of R's strengths is the ease with which well-designed
publication-quality plots can be produced, including mathematical
symbols and formulae where needed. Great care has been taken over the
defaults for the minor design choices in graphics, but the user
retains full control.
R is available as Free Software under the terms of the Free Software Foundation's
GNU General Public License in source code
form. It compiles and runs on a wide variety of UNIX platforms and
similar systems (including FreeBSD and Linux), Windows and MacOS."