PHP can run as an adjunct to IIS or Apache, so it's a breeze to add it to the mix - PHP is not a Web Server any more than ASP or CGI is.
JSP can be a little more involved since I've usually run it with TomCat. In the past I've either enabled the MS web server or the Tomcat webserver, but usually not both. Anyhow, it's not hard to set them both up - you just need to make sure they they are set to listen to different ports. Most web servers default to listening to 80 and/or 8080. Just pick the one that's not used or set it to some other address. I think Tomcat has a config file that sets the port number.
Anyhow, as long as the ports are different, they will not interfere with one another - other than speed that is.