You can install the web server and database in any order. However, if you plan on using the database driver with AOLServer, you need to have the database installed and compiled the proper DB driver. You can run a webserver without the DB hooks. you can even download the OpenACS code after you install the database, but you won't be able to use the openacs-4.tcl startup script until you have the OpenACS code installed in the proper place. I hope that helps.
