If you are considering a new startup or have an existing business with a physical server somewhere on-site (in a closet or something similar), you should consider the benefits of using a virtual server instead.
Full disclosure: I have used the virtual server company linode.com before, though I am not being paid by them and receive no benefit from my endorsement.
Let me break it down simply, by price:
At the time of this writing, a basic capable Linode virtual server costs $20/month. Through my own benchmarking tests, I've found its processor speed to be comparable with a modern medium-priced physical server.