The SQL Browser service is not required to use SQL Server. You may recall that it was the target of the attackers. Turning off this service eliminates possible attacks.
How SQL Browser works
SQL Server Browser listens for all incoming requests for SQL Server and provides info about SQL Server instances installed on the PC.
- Browsing a list of all servers
- Connecting to the correct instance
For Database Engine and SSAS, the SQL Server Browser service provides instance name & the version number. SQL Server Browser can be configured using SQL Server Configuration Manager or during a setup. By default, the SQL Server Browser service starts automatically.
More info about starting & stopping the SQL Server Browser service, http://msdn.microsoft.com/en-us/library/ms189093.aspx
If the SQL Server Browser service is not running, you are able to connect to SQL Server if you have the correct port number. If you are using SQL Server in a client-server when your application is accessing SQL Server across a network, if you stop the SQL Server Browser service, you must assign a specific port number to each instance and write to your application code to always use that port number.