I got one DNN 4.0.1 portal up and running with no problems using getting starting steps by sdwalker.

However when I try the 2nd site,, on the same machine, but a separate name,,, it fails.....the build works in VS express 2005, however i get a "page not found",, 404 error after the build runs successfully (control-F5).

can't I have 2 portals running??

Under most circumstances you would only need to install one instance of DNN and then use the database to run multiple portals from there. In IIS you would then assign your parent host portal to be the default and send any new portals to your server's IP address setting your portal's header information in the portal setup screen in Admin. This way you only need to set the header info in the DNN Database as all calls to IIS will look to the same installation of DNN. However there are cases where you may want to run multiple portals separately from each other, in which case you need to copy your DNN install folder across to a new folder and create a new virtual website in IIS with the new portal's header information and point it at your new installation. Doing this you can then do whatever you want with the install. This is useful if you want to recode some of the modules to use different graphics or layouts (such as replacing the buttons on the login module with a text link). Also some modules have hard-coded styles (yetanotherforum.net is one) where any changes made to the style is then replicated to all other portals sharing that module. As a result I personally have 3 separate folders setup running DNN2.1.2 so that I can have 3 separate forums (black, grey and blue). Alternatively I could have made 3 copies of the modules and renamed them Forum Style 1, 2 and 3 but I'm lazy and the straight copy of the folder did the job. Remember when doing this to make sure you set your security permissions on the copied folder to match the original and set your permissions in IIS to match the default site permissions as well. Another reason you may use multiple sites is when developing and testing new versions of DNN. For this reason I also have another folder with an install of DNN3.2.2 and a separate DNN3 database running on SQL. This is useful for when you want to develop a site with DNN3 features but need to retain DNN2 sites due to modules that haven't been converted to DNN3 yet. There aren't many but there are some. So in short you can setup your server as such if you really needed to...

      PORTAL 1/2  -  FOLDER 1  -  DNN2 DB1
      PORTAL 2     -  FOLDER 2  -  DNN2 DB1
      PORTAL 3     -  FOLDER 3  -  DNN2 DB2   
      PORTAL 4     -  FOLDER 4  -  DNN3 DB