Is it possible to change the portnumber to which IIS 7 is listening for incoming questions, if I have Apache and want it to listen to port 80 and IIS 7 to 8080?
And this setting should be serverwide and not just sitewide sort of a "global" change?
You need to configure this setting for the Default Web Site and for each and every other site, if you have defined any.
It can be configured in the "Bindings" section of each site properties.
In the default configuration, you will only have one site (called "Default Web Site"), which will answer to any request on any IP address the server has, using port 80; in this scenario, you only need to modify this setting to have it listen on port 8080.
you can easily change the port by going to IIS manger and then selecting Default website in left panel,then opening edit bindings and then edit the port number.For more info with screenshots go here - http://www.superpctricks.com/2013/11/running-iis-and-apache-on-same-server.html