GeoServer is the reference implementation of the Open Geospatial Consortium (OGC) Web Feature Service (WFS) and Web Coverage Service (WCS) as well as a high performance certified compliant Web Map Service (WMS).
OpenLayers is a generic mapping component, designed to consume spatial data and maps from numerous sources and display that data in a web browser. Unlike Google Maps or Microsoft Virtual Earth, OpenLayers is not tied to a particular map source. It has controls that allow the users to view and edit spatial data. OpenLayers is a project of the Open Source Geospatial Foundation and is the foundation that many commercial GIS online interfaces are built upon.
We sort of cheated here and used Microsoft SQL Express 2008. Our main reasons here are that we have lots of experience using SQL Server and lots of our customers already store data in it. Geoserver can integrate fully with it. However, GeoServer comes packaged with PostGIS - a full open sourced spatially aware database.