I have a C# web application created in VS 2003. I have a working deployment project that creates the .msi file for new installations. I need to add functionality that allows the user to upgrade to a new version. I have added a RadioButton (2 buttons) dialog to the installation user interface with an option for upgrading and an option for a new installation. If the user chooses to upgrade, the installer should procede with upgrading the necessary files. I am not sure how to make that happen. I am new to web app development and even more so to creating deployment packages, my internt searches for help have been unsuccessful. Can anyone lead me in the right direction?