This document shows you how to install Windows SharePoint Services 3.0 side-by-side with Windows SharePoint Services 2.0, so you can use the exciting new features in Windows SharePoint Services 3.0 without breaking the integration between Windows SBS and Windows SharePoint Services 2.0
Installing WSS 3.0 on a Server Running Windows SBS 2003
Installing WSS 3.0 on a Server Running Windows SBS 2003