It will install itself without messing with your system python. In addition, you can then use the conda command to install a number of versions:

  conda create -n py3 python=3.3 anaconda
  conda create -n py27 python=2.7 anaconda

That will create environments envs/py3 and envs/py27 inside your anaconda install directory.

Here you go:

    $ python --version
    Python 2.7.3 :: Anaconda 1.4.0 (64-bit)

It installs to a directory so you basically just add it to your path to get it working it doesn't change anything else on your install.

Beware though that you don't use virtualenvs with it but you use their tool conda to create your environments