I have managed to set up the python interpreter of my pydev installation to the one in my virtualenv folder following this steps:
Yei! everything works nice! but... When I use any library installed via pip, my eclipse shows an error mark in the editor, its very annoying because everything works fine!
I'm thinking of not using PyDev just because of this little detail... Does anyone know a way to solve this?
There's a little tutorial explaining about it at:
http://pydev.blogspot.com.br/2010/04/pydev-and-virtualenv.html
I believe your problem is explained there... (i.e.: after installing something you must restore your interpreter info).