I'm going to try and install apache2 on a debian box I have. What I'm after is to get apache and apache2 to run alongside each other (apache2 will run on port 81) until apache2 is completly configured and I can shutdown apache and restart apache2 on port 80. The main reason I'm going to do this is because I don't think apache2 is going to run out of the box on my webserver and I can't stop traffic until its fixed, I need a painless transition.
This way I will always have a working webserver, is this a good way of doing it?
I would apreciate any ideas from people who have converted from apache to apache2 on a critical webserver.

yeah you can do it. when you install apache2 it will create sperate directorty structure for it. and modules will have different names so you dont have to worry.

AFAIK that is the way people do to upgrade or move to a new server