RE: [CentOS] php-5 install issues on centos 4

OK, i've found php-5 RPMs in the centosplus dir on mirrors.

Sorry for my ignorance, but what's the difference between

  php-5.1.6-1.2.1.centos.x86_64.rpm

and php-5.1.6-3.el4s1.5.x86_64.rpm

? There's other such examples in the same dir.

Anyway, i opted to try installing the "el4" variety, along with the comparable RPM for php-mysql, but --after satisfying other dependencies-- ran into this:

libmysqlclient.so.15()(64bit) is needed by 

php-mysql-5.1.6-3.el4s1.5.x86_64 libmysqlclient.so.15(libmysqlclient_15)(64bit) is needed by php-mysql-5.1.6-3.el4s1.5.x86_64

Which stumps me, because the libmysqlclient14-devel RPM would seem to be the latest-greatest available in that centosplus dir. Does one have to turn elsewhere for the libmysqlclient15-devel RPM that would presumably supply the right SO file?

Thanks for any & all help.

libmysqlclient.so.15 is found in mysql-5.0.27-1.el4.centos.x86_64.rpm

Michael