[R] installing R on Mac OS X

[silvia simoni]

I have a problem in installing R-2.0.1, downloaded from the R web site, 
on mac o sx version 10.3.7.
when i launch the command ./configure i get the following error message:

  checking for C compiler default output file name... configure: error: 
C compiler cannot create executables

i've aleady insalled Xcode. the version of the gcc in 3.3.
what can i do?
thanks

silvia