The EasyWorship upgrades are complete installers that always installs a full version of the software. A previous version of the software is not required in order for it to install properly.
So, if you are switching to a new computer and purchasing the upgrade, there is no need to install the old version then install the upgrade. Just download and install EasyWorship from the downloads page and register it. That's all there is to it. You can purchase the upgrade at www.easyworship.com.