Server administrators or members of the Farm Administrators group in Central Administration can upgrade sites from WSS 2.0 to WSS 3.0. The structure and data of a site are preserved, and WSS 3.0 will make the following changes:
Upgrade the WSS technology
Upgrade the data to the WSS 3.0 database schema
Update the user rights, site groups, and cross-site groups to WSS 3.0 user permissions, permission levels, and SharePoint groups
Upgrade any Web Part customizations your organization may have implemented
Upgrade any site customizations that may have been made with a Web design program
There is no direct upgrade from SharePoint Team Services (STS) to WSS 3.0. To upgrade from STS, you must first upgrade to WSS 2.0 and ...