After the implementation peak of ERPs that occurred during the pre- and post-Y2K periods, the high-end ERP market started to saturate and major ERP vendors started to seek for new business opportunities, in special towards Small and Medium-sized Enterprises (SMEs). On the buyer side, demands for becoming more competitive in a globalized market, have been pushing SMEs to adopt ERP too. Additionally, influenced by the free/open source movement, new types of ERP licensing appeared by the beginning of the decade, creating a classification according to the basic licensing model: free/open source ERP (FOS-ERP) and proprietary ERP (P-ERP). Therefore, this paper aims at exploring the merge between SMEs, P-ERP, and FOS-ERP, by analyzing the differences between the two proposals and offering guidance for prospective adopters.