Greenstone and DSpace are widely-used software systems for digital libraries, and prospective users sometimes wonder which one to adopt. In fact, the aims of the two are very different, although their domains of application do overlap. This paper describes the systems and identifies their similarities and differences. We also present StoneD, a stone bridge between the production versions of Greenstone and DSpace that allows users of either system to easily migrate to the other, or continue with a combination of both. This bridge eliminates the risk of finding oneself locked in to an inappropriate choice of system. We also discuss other possible opportunities for combining the advantages of the two, to the benefit of the user communities of both systems.