1. Go to Start> All Programs> Microsoft SQL Server.  If you are on SQL Server 2005, it will say it there.
     
  2.  If it just says Microsoft SQL Server, an easy place to look is in Control Panel> Add/Remove Programs. That will bring up the programs installed and will show a version , such as Microsoft SQL Server 2000.
     
  3.  To get detailed information on the version , including the service pack,  if it is SQL Server Express, ?go to Microsoft Sql Server> SQL Server Management Studio and after Connecting, select "New Query". There will then be a dropdown window in the toolbar to select the "Master" database. In the Query window, type:

    select @@version and hit F5.  It will display the version , such as Microsoft SQL Server 2000 - 8.00.2050.  The 2050 indicates it is Service Pack 2 for SQL 2000. X out of the window and answer No to save the changes.
     
  4. If using full blown SQL , under Microsoft SQL Server, go to Query Analyzer. Once past the login screen, and in the query window, select the "Master" database In the dropdown  on the toolbar. In the query, type:

    select @@version and hit F5. It will show the version and service pack. X out of the window and answer No to save the changes.