My setup doesn't run. for http://localhost, i get 'under construction'

For http://localhost/aopweb, I get a 404 error.

I've been uninstalling and reinstalling IIS and SQL Express and beating my head against this going on 4 days.

Thanks Jeff. IIS works, but DNN won't install. I've read the DNN pdf (which is about 15 releases out of date??), plus various text and video tutorials on other web sites. I've created a SQL Express database, created a SQL user, created a virtual directory in IIS, unzipped the DNN files to the directory used by IIS, modified the permissions on the directory, modified the web.config file... over and over... this way and that way.  All I ever get is 404 pages. It's got to be something I've made more complicated than it really is.

The computer is a Windows Server 2003 Web Edition.

Thanks for all your help. As you noted, the problem was in IIS. Although ASP.NET got installed, it was not enabled by default.It's under Web Site Extensions.