What are the Benifits of Running Your Own DNS?

baileyjs asks: "I help run a small web development firm, and we are always trying to save money, but not at the cost of service to our customers. We currently purchase DNS services from our ISP, but are looking at getting our own rack. I was going to put some DNS servers there when I saw that Network Solutions offers free DNS. All our of domains (about 150) are currently on Network Solutions, so transfer is not an issue. Why shouldn't I use Network Solutions? Why should I build my own? What reasons, besides 'Network Solutions is Evil', can I give my boss?"