How do you upgrade from sharepoint wss3 to MOSS 2007?

Answer 1

MOSS is built on top of WSS 3.0. While the latter is availabel free for download the former is charged as per the licenses.

MOSS is installed on top of WSS 3.0. Both WSS and MOSS cannot be run on same hardware. In order to do a stand-alone configuration update, first take a backup of existing configuration including solution files, features, custom templates etc. then run the MOSS setup and then the configuration wizard.

Configuration changes that need to be done after installing MOSS on top of WSS 3.0

1. Configure Shared Services (new feature in MOSS).
2. activate features on existing site collections/existing sites explicitly.

For more information refer to related links.