Windows users will need to install some new prerequisites in order to use new w3af features.

svn up w3af (use your start menu shortcut if you want, should update to rev.1516 or higher)

install pyparsing library

http://downloads.sourceforge.net/pyparsing/pyparsing-1.5.0.win32.exe

install pydot library

http://pydot.googlecode.com/files/pydot-1.0.2.zip

extract pydot-1.0.2 somewhere:
c:\program files\w3af\extlib for example
Start > run > cmd
cd pydot-1.0.2
python setup.py install

install graphviz

http://www.graphviz.org/pub/graphviz/ARCHIVE/graphviz-2.20.2.exe

put C:\Program Files\Graphviz2.20\bin in your path (should be automatic in most cases)
right-click on My Computer, click Properties, click Advanced tab, click Environment Variables
under System Variables, click Path, click edit
add ;C:\Program Files\Graphviz2.20\bin to the end of paths list if needed
restart command prompt to reflect path changes

Check it out:

w3afclusterwin32 350x273 w3af updated prerequisites (win32 HOWTO)