I agree as I don't know which OS you are using but as far as free that I have had experience with.
Windows:->In windows these should be very easy to install.
g95
gfortran->note does not work on all windows os (check the FAQ.)
Salford Personal Edition->Installer installs a lot of goodies, nice ide, etc, but you have a pause before any executable runs as Salford let's you know you are using the free version.
For mac osx:
gfortran
g95
Intel->Demo, hard to link mkl and mp, but works excellent after everything is configured well.
Linux:->except intel, these shoudl be extremely easy to install.
gfortran
g95
Intel->there is a demo, and if you really scourge the site (it seems to get moved) there is a long term free.