MS SQL Express is free and can be downloaded from the Microsoft web site.  It is recommended for up to 10 users depending on requirements such as database size.

For more information on MS SQL Server pricing please visit the link below. If Microsoft has removed this link you can go to www.microsoft.com and search for MS SQL Pricing.

>> www.microsoft.com/sql/default.mspx

To download MS SQL 2005 Express, click on the link below. If Microsoft has removed this link you can go to www.microsoft.com and search for MS SQL 2005 Express.

>> msdn.microsoft.com/vstudio/express/sql/download