Check out these hands on labs that are available over the internet, Complete with lab guides they are a very good intro to MOSS and WSS 3.0

MOSS 2007 Hands-on Labs:

• Office SharePoint Server 2007 Functional and Architectural Overview Virtual Lab
• Enterprise Content Management with Office SharePoint Server 2007 Virtual Lab
• Organizing and Finding Resources with Office SharePoint Server 2007 Virtual Lab
• Business Solutions Using Office SharePoint Server 2007 Virtual Lab

WSS V3 Hands-on Labs:

• Introduction to Windows SharePoint Services 3.0 Virtual Lab
• Implementing and Administering Windows SharePoint Services 3.0 Virtual Lab