Automate web installer

We use the Microsoft deployment projects to install our web applications for our customers.? We need the capability to automate the installation process so users can simply click once and have our product deployed.? We gather a variety of information during our installers the first time? it is ran, and all subsequent runs populate the fields based on the prior install run (we persist the responses in? an? encrypted? registry entry). We also subscribe to various installer events to perform post installation activities (schema upgrades, etc.) so the events will have to be left in tact (or at least callable from whatever automated solution is created. The installers install .NET v3.5 based web apps on Windows 2003 servers (IIS 6.0).