pip fetches the source code of the packages you're trying to install and compiles them. So if you don't have a compiler installed and configured it will fail to do so for packages which contain extensions written in C, which in this case applies to pyreadline
, PIL
and cython
.
easy_install uses the precompiled packages from pypi (at least for windows if they're available), which means you don't need to compile everything yourself.
For pure python packages it's no problem using pip instead of easy_install, and if you have a compiler and the neccessary build dependencies installed it should also work.