Does the Fortran77 version of NR run
in Mac OS 10.2 ?

Javier,
All Numerical Recipes code is source code for ANSI/ISO standard compilers. So, if you have a Fortran compiler under Mac O/S X then you should be fine.
Searching the web, I notice that Absoft and NAG have commercial Fortran compilers specifically for Mac O/S X, and that people have succeed in using the free g77 compiler also. A good summary web page seems to be
http://gravity.psu.edu/~khanna/hpc.html
(By the way, any Fortran 90/95 compiler can handle NR in Fortran 77 without difficulty, since the languages are backwards compatible. We do recommend using NR in Fortran 90, however, if you are comfortable with the newer language features.)
Hope this helps.
Bill Press

Also check out the fink project for MacOSX (I believe the link is something like fink.sourceforge.net) as they have executables already set up for OS10.2, which is quite nice. The g77 performance is exactly the same as in linux or unix environments, and absolutely portable.