If you are installing IWS on Windows XP - as a quick evaluation - you might want to increase the connection limits of IWS.
Windows XP Professional runs IIS version 5.1 and comes with a 10 connection limit. Often that's not enough when you are testing a site from multiple browsers (or multiple locations). You can easily increase the limit to the hardcoded maximum: 40 connections.
Make a command prompt window (start, run, cnd.exe) and issue these commands.
The first command connects you to the adminscripts folder. The second command runs a script that sets the MaxConnections value in the IIS metabase to 40 (the maximum allowed). The third command (iisreset) shuts down and then restarts IIS.