Microsoft Office Sharepoint Server (MOSS) is the BIG, rich brother of Windows Sharepoint Services (WSS). Since there are already many articles on WSS vs MOSS online, I would not want to repeat here. The definitive article is available from Microsoft
here. What I would like to discuss is my preference for WSS.
1. WSS is free! Well, almost. You still have to pay for Windows Server. If you have purchased Windows Server 2003, then you already own the license. It is still a free bundle with Windows Server 2008.
2. WSS is an affordable portal platform for connecting to your customers, suppliers and business partners. To extend WSS to external users, an affordable USD2,500 license (Windows External Connector) provides unlimited number of users on a single server box.
3. WSS is lean. For what we do with WSS, building collaborative applications and business reporting, WSS offers a lean, high performance and scalable platform that is easy to manage and administer. We use it because we can do everything that we wanted to do and more; even when compared to MOSS.
4. WSS is extendable. MOSS leverages on WSS. If Microsoft can extend on WSS features to value add, so can you. We took the most essential features of WSS and enhance into a dynamic collaborative applications platform where business users can build their own systems without any programming.
5. WSS is upgradeable. Use it today, enjoy all its benefits. When your ROI is so evident that you can justify your invesment for MOSS, that upgrade path is still available to you. At the architectural level, both MOSS and WSS are essentially the same. The in-place upgrade path simply means that you can have your cake and eat it.
All things considering, I feel that WSS is one of the greatest contribution that Microsoft have ever delivered to its customers. The fact that so many customers actually purchases MOSS licenses means that they have many grateful customers who want to return the favor.