Python

"Python is a remarkably powerful dynamic programming language that is used in a wide variety of application domains."

• Python.org - you can get Python here.
  
• Think Python - book that teaches programming with Python. The book is available for free.

Do more:

There are some packages good for scientific computing and plotting. Namely: Numpy, Scipy and matplotlib. They may not be yet available for Python 3.2. If you are stubborn like me and don't want to go back to Python 2.7, you can get some unnofficial builds from the website of Christoph Gohlke from the University of California --windows only :-(

Have fun!