Microsoft SQL Server QoS

Hi All

We are having problems with our Resource Usage on a SQL Production server.

What is the best way to setup some form of QoS on a SQL server to make sure that one query does not use all of the resources on the Server when other queries also needs resources.

In our case we have users running reporting throughout the day and many other queries that does not take more than 2 min at most. But then we have a query that needs to run at that same time for 3 hours, that query is resulting in slow speeds towards the users as it is taking all of the resources.

Thanks in advance