[otrs] Multiple Service Types

I was wondering if someone could suggest the accepted approach(es) for handling the following scenario... A company has help desk department that supports only it's employees. There are three categories of support tickets (ie hardware, software, other). Each category should have it's own queue. Each queue to be handled and managed by specific agents/agent groups. I am not clear on... Do I setup separate customer for each category? or is there a way to specify category on the ticket? If later how do I tie category to a queue? and how do I assign agents to handle specific queue? etc... Any help is greatly appreciated Thanks in advance