I have setup XAMPP at work. It comes with Apache 2, MySQL, phpMyAdmin and a whole bunch of stuff.
The Apache resides at
http://localhost (port:80)
I installed Microsoft Visual Studio Express Edition and also setup IIS via Windows Control Panel as I wanted to try MSSQL Server Express Edition .
Now after installing IIS, Apache Refused to start.
[code lang="PHP"]Only one usage of each socket address
is normally petmitted. :make_sock could not bound to address:0.0.0.0:80
no listening sockets available , shutting down
Unable to open logs
[/code]It was because there was a conflict in the port 80.
Now i went to the website properties in IIS and changed the port no to 9090 from 80.
Now restarted IIS and tried to start apache
Now similar error but diff port
[code lang="PHP"] Only one usage of each socket address
is normally petmitted. :make_sock could not bound to address:0.0.0.0:443
no listening sockets available , shutting down
Unable to open logs
[/code]Now i suspected the conflict was in the SSL port so tried digging through the XAMPP files.
found this file httpd-SSL.conf in \\apache\conf\extra\
Navigate to this line.
[code lang="PHP"]# When we also provide SSL we have to listen to the
# standard HTTP port (see above) and to the HTTPS port
#
# Note: Configurations that use IPv6 but not IPv4-mapped addresses need two
# Listen directives: "Listen [::]:443" and "Listen 0.0.0.0:443"
#
Listen 443
[/code]change 443 to say some port like 4499
1 more change
[code lang="PHP"]# General setup for the virtual host
DocumentRoot "c:/web/xampp/htdocs"ServerName localhost:4499
ServerAdmin admin@localhost
[/code]Voila !!!
Now i can run IIS and Apache parallelly 
That means i can work with ASP and PHP at the same time
