I would run on the same computer Collabnet Subversion Edge 3.0.1 with its Apache instance and XAMPP 1.8.0 with its instance of Apache for others intranet services.
To avoid any conflict, I changed the port for XAMPP Apache to 81, but any instance is launched as second fail to start.
Further, if SubversionEdge is run first, the Control Panel of XAMPP looks like:
10.45.48 [apache] Possible problem detected!
10.45.48 [apache] Port 80 in use by "httpd.exe"!
Even if the XAMPP Apache is not set as a service.