Welcome to the wonderful world of trying to run Apache on a WinDoze box!
First, please decide whether you're using XP or Vista as Vista (and Win7) security makes things almost unbearable (XP was easy).
Let me treat it as Vista/Win7.
First, you really don't want to have to use :8080 all the time so I'll recommend that you UNINSTALL Apache and reboot your computer (to clear from Services).
Second, get into your services (Start|Run services.msc) and STOP IIS and change the properties to Manual Start (to allow Apache to start and capture port 80).
Third, you may now run the WinDoze Installer for Apache but do NOT install into Program Files! Create another web directory (c:\web\Apache - or I have created a drive partition and installed there as W:\Apache). That will eliminate the PITA with editing the httpd.conf for Apache and php.ini for PHP.
Fourth, create a checklist for updating the configuration files as you have not done that correctly. Install MySQL, install Apache then install PHP (merely unzip into your c:\web\PHP or W:\PHP directory) then edit the httpd.conf to add PHP to Apache and edit PHP's ini file.
Several years ago (under XP), Kevin's book (Chapter One, Installation) had to be read through and things reordered to work correctly. With all the different versions of WinDoze since XP, the "trick" was to install outside the few directories "protected" by the OS. All Kevin's other information is quite good.