[CentOS] gmp package installation on CentOS 5.2

Hello,

Last year, I installed CentOS 5.2 on an HP Proliant Server. Along with other packages, the gmp and gmp-devel version 4.1.4 packages were installed. To the best of my knowledge these packages do not come from the gmp team.
Recently, I built an rpm package for gmp 5.0.1 for CentOS 5.2. I tried to update the gmp package by command

rpm -Uvh gmp-5.0.1-1.x86_64.rpm

but the update failed because the libgmp.so.3, libgmpxx.so.3 and the libmp.so.3 are needed from
gcc-gfortran, php, php-cli, guile and gmp-devel packages.

What kind of dependency exists between these packages and gmp?
Could I forced the update without affecting the operation of the above packages?

Since It is better to compile gmp 5.0.1 with the more recent gnu c compiler, 
is it safe to update gcc, gcc-gfortran and gcc-c++ on CentOS 5.2 to the more recent version appeared for CentOS 5.5?

Regards,

Panagiotis Nastou,
Dpt of Mathematics
University of Aegean
Karlovasi, Samos, Greece