I developed a small app and have distributed it to several clients. Recently I 'overhauled' the entire app to include much more functionality and many new modules. In the course of the rewrite I had to change several table structure changes and add a few tables. The new version has the ability to upgrade from the previous version. I still want to be able to offer this program as a 1 file download form our website. How can I get the app to check for previous versions and install as new if no previous version exists or upgrade if needed. I WANT THIS TO HAPPEN ONLY ON INSTALLATION. I don't want the program to check for previous versions everytime it is run. Is there such a thing as a 'pre' setup executable? Any help would be appreciated.