typo fix

doc/INSTALL.rst

@@ -44,7 +44,7 @@ using ``virtualenv`` as follows::
 
 If you don't already have ``virtualenv`` installed on your system, download
 the latest release from the `virtualenv PyPI page
-<http://pypi.python.org/pypi/virtaulenv>`_, unpack it, and install it, e.g.::
+<http://pypi.python.org/pypi/virtualenv>`_, unpack it, and install it, e.g.::
 
   $ wget http://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.4.5.tar.gz
   $ tar xzf virtualenv-1.4.5.tar.gz