**Windows**
For Windows, you must have Python 2.6 installed. Note that
some problems have been reported with VISTA in the past.

**Mac OS X**
For Mac OS X binary installation, you must have Python 2.5
installed. Also, you must have gcc installed, to get it, you
need to download and install Xcode, which is free. Search
for "download Xcode" in google to find it. 

** Mac OSX with snow leopard **
To run NAST on snow leopard, you will need to use the 2.5
version of python (which is a 32bit application as opposed
to 64bit). You can change the default python used by typing:
"defaults write com.apple.versioner.python Version 2.5"
into your terminal. If you do not want to change the default
python, make sure to type "python2.5" instead of "python"
for every python command you run.
You will also need to place the file "libOpenMM_static.a"
into the nast-0.5/lib/osx/ directory. This file is posted
under the Mac OSX heading in the downloads section.

**Unix**
For installation from source (only method available for
Linux), you must have Python 2.5 or 2.6 installed.

**64bit Unix**
Download the libOpenMM_static.a file under the source
section and replace the file with the same name in your
nast-0.5/lib/linux/ directory.