S-Plus is available on all stat servers and on vet. Under Unix, you can invoke S-Plus by typing command Splus. If S-Plus does not come out, add /usr/local/bin to your $PATH or use full path name /usr/local/bin/Splus.
The Unix version of S-Plus ( currently v6.0 Release 1) does not have a graphics user interface as its windows counterpart. It is terribly difficult to enter command, edit S-Plus script using only command line. Luckily, ESS greatly improves the usability of Unix S-Plus, please refer to the next section.
There are many good S-Plus books. The Basics of S and S-PLUS by Andreas Krause and Melvin Olson, Modern Applied Statistics with S-PLUS by W.N. Venables and B.D. Ripley are two classic ones. The first book is a good introduction while the second on can be used as a good reference. Dr. Baggerly has put together a two part S-Plus tutorial. It has been modified and now resides at helpdesk http://www.stat.rice.edu/ helpdesk. However, believe me or not, the best way to learn S-Plus in a systematic way is to follow the S-PLUS programmer's guide which come with S-PLUS distribution and is available in the library.
I'll reiterate that as a student you can install S-Plus on your home windows machine. Another alternative is the `free' version of S-plus, known as R http://www.r-project.org/, which has most of the same commands, runs most S-plus scripts, but, from a computer science perspective is better written. It was lacking of some important S-Plus features like trellis graphics but the huge user community has written many R packages, including a recent package that does trellis graphics, and makes R a better choice under many circumstances.
R is available free for all platforms. You can download and install the windows version from R Download Page http://cran.r-project.org. On stat network, R is entailed under helpdesk along with all packages on R package webpage http://cran.r-project.org/src/contrib/PACKAGES.html. It is preferred that you start R with ESS but you can also start it directly by typing command /home/helpdesk/bin/R.