Ekrem Önsoy
Hello,
SQL Server 2005 Express Edition is installed with Visual Studio 2005 by default. Of course, if you select that choice when you setup Visual Studio.
So it's quite normal SQL Server Express Edition is installed in your environment too. If you want to install another edition of SQL Server, then I suggest you to obtain an evaluation copy from:
http://www.microsoft.com/sql/downloads/trial-software.mspx
Regarding to the problem, first ensure that your SQL Server service is running. You can run services.msc or SQL Server Configuration Manager to see that. If it insists not running, then tell us the error message. Besides, you better take a look at the Event Viewer to see if there is any error message specific to SQL Server's service.