With the two new Search Server 2008 products that were recently released (www.microsoft.com/enterprisesearch), there have been questions about when can the Express product be used and when is the full Search Server 2008 product required?
Q: Does Search Server 2008 Express require SQL Server 2005 Express Edition?
A: No, Search Server Express can still use SQL Server. If you choose the Basic install, then SQL Express will be installed. If you choose Advanced install, then you can select a SQL Server instance to use.
Q: Does Search Server 2008 Express have a capacity limit, or ceiling, on the number of documents it can index?
A: No, Search Server 2008 Express does not have a limit on the number of items indexed. If you are using SQL Express as the back end, then SQL Express has a database size limit of 4GB, which you will be restricted to.
Q: So, the difference between the two versions is the redundancy on the front-end servers?
A: Right. Specifically, with Search Server 2008 Express, you cannot have more than one query server in your farm.