the fact that phpinfo displays tells us that php is running fine.
about halfway down on phpinfo.php there'll be a MySQL section... if you have the mysql modules on.
if not, open your php.ini (not sure where this is stored on RH, i am using w2kpro). there is a section called dynamic extensions. If you have the mysql php driver (mysql.so on RH, mysql.dll on Win) then it's usually just as easy as adding a line (or uncommenting if it already exists) that says extension=mysql.so
follow this plan for other extensions, ie gd, sockets etc