
Do you use waveguides for your installs, cause NO coax can carry signals in that range for any reasonable distance. You are correct however that dish and cable (note:
cable not cable internet) use separate enough frequency ranges that they should not interfere. Your numbers, however, are significantly off. Cable uses 5MHz - 850MHz (With cable internet using the higher end of that band), while dish uses from 900 - 2150MHz (Unless you are using all legacy equipment, in which case it is 900 - 1450MHz).
So, for normal cable, you are correct, this is no problems. When you get into cable modems, it really depends on the provider, and the signal quality at your home. Due to the fact that cable modems generally use the upper range of the available bandwidth, you can run into some serious problems trying to use diplexers as they tend to significantly degrade the higher frequencies.