Fix:
I chose the "ISAPI & CGI Restrictions" after clicking the server name (not the site name) in IIS Manager, and right clicked the "ASP.NET v4.0.30319" lines and chose "Allow".
After turning on ASP.NET from "Programs and Features > Turn Windows features on or off", you must install ASP.NET from the Windows command prompt. The MIME types don't ever show up, but after doing this command, I noticed these extensions showed up under the IIS web site "Handler Mappings" section of IIS Manager.
C:\>cd C:\Windows\Microsoft.NET\Framework64\v4.0.30319
C:\Windows\Microsoft.NET\Framework64\v4.0.30319>dir aspnet_reg*
Volume in drive C is Windows
Volume Serial Number is 8EE6-5DD0
Directory of C:\Windows\Microsoft.NET\Framework64\v4.0.30319
03/18/2010 08:23 PM 19,296 aspnet_regbrowsers.exe
03/18/2010 08:23 PM 36,696 aspnet_regiis.exe
03/18/2010 08:23 PM 102,232 aspnet_regsql.exe
3 File(s) 158,224 bytes
0 Dir(s) 34,836,508,672 bytes free
C:\Windows\Microsoft.NET\Framework64\v4.0.30319>aspnet_regiis.exe -i
Start installing ASP.NET (4.0.30319).
.....
Finished installing ASP.NET (4.0.30319).
C:\Windows\Microsoft.NET\Framework64\v4.0.30319>
However, I still got this error. But if you do what I mentioned for the "Fix", this will go away.
HTTP Error 404.2 - Not Found
The page you are requesting cannot be served because of the ISAPI and CGI Restriction list settings on the Web server.