Trying to remove a duplicate installation of apache2

First off, I'm a complete newb so bear with me.

When setting up my Ubuntu box, I was able to install apache2 just
fine. Unfortunately, it did not work well (or at least I couldn't get
it to play nice) with mongrel_rails. I followed a few walkthroughs and
got Capistrano to get a working version of apache up and running and
things were great.

Until I rebooted the machine. Now the server tries to load the
incorrectly configure apache2 living in /etc/apache2 instead of the
correctly configured apache2 living in /usr/local/apache2

How do I tell my machine to load apache2 from /usr/local/apache2
instead of /etc/apache2?