Links to other post of this series
Part 1: This post
Microsoft Search Server 2010 is an enterprise search solution that is free to download, easy to configure and yet powerful.
Microsoft Search Server 2010 Express is
Microsoft has added many features to Search Server 2010 Express.
1) Query Suggestions: Query suggestions for end users. Users see the Query suggestion as they type queries as well as suggestion after they run queries, this is accomplished by “Did you mean” suggestion.
Note: Remember these suggestions are based on past queries from other users
2) Related Searches: A web part showing related searches for the given query.
3) Multiple Sources: The following connectors come out of the box in Search Server 2010 Express:
Windows file shares
Exchange public folders
IFilters for additional repositories
Structured content in databases
Federation object model
4) Relevance Model: Incorporate your workforce’s preferences and behavior into the relevance model. Extracted metadata and phrase matching also affect document rank.
5) Scale up to 10 Millions Items: It can scale up 10 Millions items.
Overall Search Server Express 2010 is good choice for SharePoint Foundation 2010 and if you have less data for search. Also remember the limitation of Search Server Express 2010 that it can be used on one web farm only.