Primary decision factors: Security, staff experience
Our discussion on the choice of a Web server was short. We put Microsoft's Internet Information Server and Apache on the table, and picked Apache. Security was the primary driver, though our familiarity with Apache also worked in its favor. With nasty viruses and worms around, and considering that even a firewall won't stop attacks on IIS, Apache won with little argument.
Web Application Server: IBM WebSphere 4.01, microsoft Windows 2000 Server, Dell PowerEdge 2650
Primary decision factors: Cost, experience, availability of additional staff