Compiling Apache with the 'prefork' or 'worker' MPM

While trying to install Phusion Passenger ( http://www.modrails.com/ ) , I came across the following message:
WARNING: Apache doesn't seem to be compiled with the 'prefork' or 'worker' MPM

Passenger has only been tested on Apache with the 'prefork' and the 'worker'
MPM. Your Apache installation is compiled with the '' MPM. We recommend
you to abort this installer and to recompile Apache with either the 'prefork'
or the 'worker' MPM.

When I try to continue the installation , all seems to go well, however, after updating my apache configuration , I get the following error :
Syntax error on line 1321 of /usr/local/apache/conf/httpd.conf:
Cannot load /usr/lib/ruby/gems/1.8/gems/passenger-2.0.3/ext/apache2/mod_passenger.so into server: /usr/lib/ruby/gems/1.8/gems/passenger-2.0.3/ext/apache2/mod_passenger.so: undefined symbol: apr_bucket_destroy_noop
/usr/sbin/httpd start: httpd could not be started


So, I now suppose that it may be the best to recompile apache with one of those "MPM"s, however, I don't have experience with compiling apache, let alone with extra items.

Extra Information, from phpinfo file:
APACHE_INCLUDE       no value
APACHE_TARGET       no value
Apache Version       Apache/1.3.39 (Unix) mod_auth_passthrough/1.8 mod_log_bytes/1.2 mod_bwlimited/1.4 PHP/4.4.7 FrontPage/5.0.2.2635.SR1.2
Apache Release       10339100
Apache API Version       19990320
User/Group       nobody(99)/99
Max Requests       Per Child: 0 - Keep Alive: on - Max Per Connection: 500
Timeouts       Connection: 50 - Keep-Alive: 15
Server Root       /usr/local/apache
Loaded Modules       mod_auth_passthrough, mod_log_bytes, mod_bwlimited, mod_php4, mod_frontpage, mod_setenvif, mod_so, mod_expires, mod_auth, mod_access, mod_rewrite, mod_alias, mod_userdir, mod_actions, mod_imap, mod_asis, mod_cgi, mod_dir, mod_autoindex, mod_include, mod_status, mod_negotiation, mod_mime, mod_log_config, mod_env, http_core

Thanks!