I haven't used a WAMP package yet. I have installed Apache, MySQL and PHP individually myself and have had no problem with anything interfering with the normal operation of any programs. I go into the Services screen in the Control Panel and set the services' startup type to manual from automatic so they don't run when the computer is booted. I also put an line in an htaccess file in the document root to deny connections from all but localhost.
You should have no problems allowing these services to run when you are not using them. I haven't and I've been using them for years.