Update README.md

Author: CamDavidsonPilon

README.md

@@ -103,8 +103,10 @@ The contents are updated synchronously as commits are made to the book. You can
 Installation and configuration
 ------
 If you would like to run the IPython notebooks locally, (option 1. above), you'll need to install the following:
--  IPython 0.13 is a requirement to view the ipynb files. It can be downloaded [here](http://ipython.org/ipython-doc/dev/install/index.html)
--  For Linux users, you should not have a problem installing NumPy, SciPy and PyMC. For Windows users, check out [pre-compiled versions](http://www.lfd.uci.edu/~gohlke/pythonlibs/) if you have difficulty. 
+-  IPython 0.13 is a requirement to view the ipynb files. It can be downloaded [here](http://ipython.org/ipython-doc/dev/install/index.html) 
+- Necessary packages are PyMC, NumPy, SciPy and Matplotlib.   
+   -  For Linux/OSX users, you should not have a problem installing the above, [*except for Matplotlib on OSX*](http://www.penandpants.com/2012/02/24/install-python/).
+   -  For Windows users, check out [pre-compiled versions](http://www.lfd.uci.edu/~gohlke/pythonlibs/) if you have difficulty. 
    - also recommended, for data-mining exercises, are [PRAW](https://github.com/praw-dev/praw) and [requests](https://github.com/kennethreitz/requests). 
 
 -  In the styles/ directory are a number of files that are customized for the notebook.