Take a look at
http://dishchannelchart.com/ for lotsa info... you can see which bird your locals are on.
The Dish500 can see 110 and 119 birds at the same time. The HD channels are on the chart down near the bottom
There are two flavors of SuperDish... both flavors see 110 and 119 (like the Dish500 does) and the third bird is either 105 or 121. To keep things complicated, there are also
148 and 61.5 orbital locations for international, Sky Angel, a few HDTV and other misc. local channels - if you need to get 4 birds then you'll need a SuperDish, a separate Dish300 (looks at one sat only) and some exotic switch wiring.