In the USA, the two main DBS satellite TV providers are DirecTV and Dish Network. DirecTV, being the first DBS system, is technically unique (reportedly even down to the packet size). Dish Network uses a variation of the international standard DVB.
For comparison, in Canada (Hi!), there is Bell ExpressVu that uses the same technical standards and equipment as Dish Network; and StarChoice that is FSS (not DBS). Of course, the Canadian systems have their own satellites and programming. Even if the Bell/Dish receivers are often the same, they have their own firmware loads, model numbers and serial number ranges.
Getting back to your question as I think you intend, the two US systems are using multiple orbital slots. Most home installations are aimed at just the two primary orbital slots. If you want even more channels (niche, ethnic, local), then you might have to get the triple dish (and possibly an updated receiver) to cover three orbital slots.
If you were asking about 'Dish Network', then the two primary slots are at 110W and 119W. That's all that most people have installed. The 'extra' slots are at 61.5W, 129W, and 148W. What channels are on what slot? I wouldn't know. You'd have to ask your local dealer exactly what is required to meet your needs.
A good website to see the satellites is
shows the orbital slots covering North America.
If you have an old Dish receiver, you might still need a new one to be compatible with the more complicated dish installation. The old reciver can normally be put into service in another room. There might be a requirement for more RG-6 cables from the dish to inside.
The equipment and installation costs should be negligible when compared to the subscription fees in the long run, so go for it (get a dual-tuner High Def PVR). If you can make sure it's the latest MPEG-4 compatible version, then you'll be set for a few years.