My initial thought is that you are missing an entry in the hosts file. Something like "127.0.0.1 localhost", however, you mention that you are getting a 404 error. That means that the webserver is connecting to your client/browser and responding to the request for a particular webpage.
I'm not familiar enough with Windows 7, however, I'm pretty sure that it does not include a webserver by default. Also, unless you actually code, build and run a webserver application using netbeans you're not going to get the desired response.
When it comes down to it.... your issue is going to be one of the following:
1) you're serving static documents and the webserver is not configured to serve the files from whatever the proper DOCROOT should be. This includes PUBLIC folders in the user's directories. (the basic apache install include a basic homepage)
2) you have a dynamic webserver application where the controller is looking at the application path in order to decide what page to display or what function to execute. (see MVC - Controller). Basically incomplete implementation.
3) yet another configuration error: your website might actually define a virtual domain. (something other than localhost) so when you look for localhost in the URL the server might not be configured to provide a default page.