A bit more searching found two articles on using your computer as a development platform for Apache and Nginx.
by mike plate at mikeplate.com
http://www.mikeplate.com/2011/11/06/stop-http-sys-from-listening-on-port-80-in-windows/
His article does a good job of describing what http.sys is and how Win 7 uses this protocol stack. Applications subscribe to this stack, defining what it wants and then is alerted to incoming headers. His idea to get around this is to use netsh to bind http.sys to IPv6 to free IPv4's port 80. http://localhost then goes to http.sys on IPv6. Then he runs a Nginx server on IPv4's port 80
He also suggests editing the C:\Windows\System32\drivers\etc\hosts file adding "127.0.0.1 local". "local" now goes to the IPv4 address 127.0.0.1. Type "local' and you are connected to the IPv4 127.0.0.1. This would be the Apache server in XAMPP.
This whole sequence suggests to me as to whether netsh could be used to create another 127.0.0.x address or another IP interface on the NIC card to assign the entire XAMPP programs to use. How will this work when your working with a wireless connection?
Second link at the end of Mike Plate's article is an article from the Montreal SEO Company, "Configuring nginx with PHP on windows"
http://www.montrealseocompany.com/2012/05/04/configuring-nginx-with-php-on-windows/
Their article is focused on Nginx and PHP but you can substitute Apache for Nginx. They use the a different TCP port number by modifying the configuration files to handle this issue. This includes changes to PHP start command and markup code. They also suggest using using Telnet as a simple debug tool.
Okay looking at Mike Plate's solution to me looks better if Windows applications accessing "localhost" all use that name to get to the local Win 7 http.sys listener. If there are Win 7 applications coded to use 127.0.0.1 literal then there could be some undocumented anomalies. The choice would then be to change to another TCP port number.
Mike Plate's solutions would require XAMPP Windows installer version to add steps to offer to change ports, add interfaces, modify the hosts file, and modify the start batch files. Maybe it is a good idea to check port usage for all the packages and offer to change the configuration.
Considering that Microsoft first introduced the http.sys subscription listener service in Win Server 2003, I have to speculate that an Apache project or some other open source project has already solved this problem. That's the next search.
Cheers,
JSW