Thanks for all the help, folks.  I've been trying everyone's suggestions, and here's a progress report.  I'm not sure if I should edit the code from here.  It seems like another configuration problem....

• Navigate from the DOS prompt to c:\windows\microsoft .net\framework\v2.0.50727\ then type aspnet_regiis -ir and it will install and associate the mime types.
  Looked under MIME types but found no .ASP(X) there.
• Control Panel\Programs\Programs and Features\Turn Windows features on or off.  Under Internet Information Services, expanded "IIS 6 Management Compatibility" and checked each item under it.  Under "World Wide Web Services\Application Development Features" ASP.NET was already checked.
• Browsed to localhost/dnn and got a long error message which I failed to copy.  It said I should set up the app to use the classic application pool and gave the following command, which I ran as Admin in a CMD shell. "C:\Windows\System32\inetsrv>%systemroot%\system32\inetsrv\APPCMD.EXE migrate config "Default Web Site/"  
  It responded with Successfully migrated section "system.web/httpHandlers"
• Browsed to localhost/dnn and got the following error message.  (This is also the point where I started documenting my progress.)
  Parser Error Message: It is an error to use a section registered as allowDefinition='MachineToApplication' beyond application level.  This error can be caused by a virtual directory not being configured as an application in IIS." 
  I took this to mean I should convert the virtual directory to an application...
• Started IIS Manager, right-clicked my dnn virtual directory and chose "Convert to Application" and pressed "OK"  (still no .ASP(X) under MIME types, btw)
• Browsed to localhost/dnn.  Much disk churning, then, "Object reference not set to an instance of an object."  Turned debugging on in web.config.
• Browsed to localhost/dnn.  "Object reference not set to an instance of an object."
  

  Object reference not set to an instance of an object.

  Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
  
  Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.
  
  Source Error:
  
  

  Line 84: If AutoUpgrade Then Line 85: If UseWizard Then Line 86: Response.Redirect("~/Install/InstallWizard.aspx") Line 87: Else Line 88: Response.Redirect("~/Install/Install.aspx?mode=install")

  
  Source File: c:\dnn\App_Code\Global.asax.vb    Line: 86
  
  Stack Trace:
  
  

  [NullReferenceException: Object reference not set to an instance of an object.] System.Web.HttpHeaderCollection.SetHeader(String name, String value, Boolean replace) +121 System.Web.HttpHeaderCollection.Add(String name, String value) +49 System.Web.HttpResponse.GenerateResponseHeadersForHandler() +162 System.Web.HttpResponse.IntegratedFlush() +10 System.Web.HttpResponse.Flush(Boolean finalFlush) +107 System.Web.HttpResponse.Flush() +17 System.Web.HttpResponse.End() +106 System.Web.HttpResponse.Redirect(String url, Boolean endResponse) +498 System.Web.HttpResponse.Redirect(String url) +6 DotNetNuke.Common.Global.CheckVersion() in c:\dnn\App_Code\Global.asax.vb:86 DotNetNuke.Common.Global.Application_Start(Object Sender, EventArgs E) in c:\dnn\App_Code\Global.asax.vb:321 [HttpException (0x80004005): Object reference not set to an instance of an object.] System.Web.HttpApplicationFactory.EnsureAppStartCalledForIntegratedMode(HttpContext context, HttpApplication app) +3381770 System.Web.HttpApplication.InitSpecial(HttpApplicationState state, MethodInfo[] handlers, IntPtr appContext, HttpContext context) +167 System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +270 System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext, IntPtr& errorMessage) +260 [HttpException (0x80004005): Object reference not set to an instance of an object.] System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +3539851 System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +69 System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +669

The InstallWizard.aspx file is there in its proper location.

Time for supper....

I'm getting the same error. I tried opening the installwizard and the install pages directly, but I keep getting the same error. Has anybody figured this out?

Thanks dpiccolo,

That worked for me too.  I had been trying everything I'd read about to date. Thanks again