mcrypt installation problems

Can anyone point to information on how to install mcrypt support for PHP. I tried the PHP mcrypt pages but they are quite lacking in details. I downloaded libmcrypt and got that installed fine. I also downloaded mcrypt (do I really need it?) but that wouldn't configure. It complains that: checking for libmcrypt - version >= 2.5.0... no *** Could not run libmcrypt test program, checking why... *** The test program compiled, but did not run. This usually means *** that the run-time linker is not finding LIBMCRYPT or finding the wrong ... I tried compiling PHP with --with-mcrypt=/usr/src/mcrypt-2.6.3/ (the locate of the mcrypt source files) but that gave me an error when I did make: cc1: warning: changing search order for system directory "/usr/local/include" cc1: warning: as it has already been specified as a non-system directory /usr/src/php-4.3.0/ext/mcrypt/mcrypt.c:229:1: warning: "MCRYPT_FAILED" redefined In file included from /usr/src/php-4.3.0/ext/mcrypt/mcrypt.c:34: [...] Questions: 1- Do I need both libmcrypt AND mcrypt? 2- What is the installation procedure? I tried the obvious "./configure && make" combination but to no avail ... Thanks! Jc