Packages - When it comes to doing scientific work it can become difficult to install some of the packages like matplotlib, IPython and sci-kit learn as you need to have the compilation environment set up properly. Anaconda solves this by making it possible to download a full python stack for any platform. It includes more than 125 Python Packages.
Environments - When it comes to managing your packages and environments it also bundles a package manager. Enter Conda, the only package and environment control system I think I will need. Create environments. Update packages. No problem. And yes PIP and easy_install also still work.
I will take you through a presentation by Travis Oliphant from Continuum Analytics detailing Anaconda and Conda.
Some Download Links