Here is one way....

SqlConnectionStringBuilder cnStr = new SqlConnectionStringBuilder();

cnStr.UserID = this.txtUsername.Text;

cnStr.Password = this.txtPassword.Text;

cnStr.DataSource = this.cboSQLServer.Text;

cnStr.ConnectTimeout = 30;

SqlConnection cn = new SqlConnection();

cn.ConnectionString = cnStr.ConnectionString;

cn.Open();

System.Data.DataTable dbList = cn.GetSchema("Databases");

foreach (System.Data.DataRow row in dbList.Rows)

{

this.cboDatabase.Items.Add(row[0]);

}