If you’re running easy_install, pip, zc.buildout, virtualenv, or a similar tool on Windows, and it says:
unable to find vcvarsall.bat
The issue is that you need a compiler installed on your system. Many people seem to recommend MinGW, but I’ve been there, and it’s a huge pain in the butt.
Just download and install Microsoft Visual Studio Express 2008 which is free. Please note the 2008 part. This must match the compiler that Python itself was built with, and that’s the 2008 (NOT 2010) version. (See http://mail.python.org/pipermail/python-list/2010-April/1242706.html for more details why 2008 is important.)