I have Python 2.7 and NumPy installed. I have downloaded pre-built binaries for SciPy, but the install script fails with this error:
To install SciPy on Windows you have to have a fortran compiler installed. The SciPy project recommends MinGW. See Building and installing SciPy. To install MinGW follow these instructions: HOWTO Install the MinGW (GCC) Compiler Suite. Then before you run pip or easy_install to install SciPy make sure that you have MinGW added to your path. See MinGW Installation Notes - Environmental Variables
A side note, It would be easier to use either the Enthought Distribution (part of the initial install) or the Active State Distribution (through pypm 32-bit only) as they already have precomiled binary packages for SciPy. Or, you could use the SciPy precompiled binary package installer for Windows.