A lot of HDfan's post is not accurate.
DirecTV broadcasts from 99, 101, 103, 110 and 119, and then also from 95 (international channels) and from 72.5 (local channels in a few areas). HD national and local channels come from 99 and 103 - there are a couple on 110 and 119 but these are duplicated on 99/103 and the 110/119 versions will be going away soon.
119 carries some cities' SD locals, also carries the ethnic package, and the Hope channel.
If you don't have International, then most people need to receive signals only from 99/101/103, plus 119 if you are in one of the cities that get SD locals from 119. In Boulder your SD locals come from 101, so you don't really need 119 unless you have the ethnic package or want to watch the Hope channel.

The Slimline dish which you need for HD programming comes with different LNBs, the dish is actually the same. The LNBs are the SL3, SL5, SL3 SWM and SL5 SWM. The SL5 sees all the five satellite slots - 99/101/103/110/119, the SL3 just sees the three at 99/101/103. For you, you can use the SL5, or if you don't need 119, you can use the SL3. (Ignore 110, the few HD channels on 110 are going away - and are duplicated on 99/103 anyway). All HD receivers and DVRs on the regular SL3 and SL5 will need b-band converters to receive HD from 99/103, EXCEPT the H23 and HR23 which have wide-band tuners and so don't need the BBcs.
Or you can also use the SWM versions of the LNBs, which will give you a single wire into the house and allow you to connect both tuners of a DVR with a single cable, and don't need the BBCs.

All the types of receiver and DVR will work with the regular LNBs, but only certain types will work with SWM (D12, R16/22 and all the Hx series of receivers and the HR2x series of DVRs).

You have to use the power inserter with the SWM LNBs, because it powers the electronics in the dish. You can connect up to eight tuners to the SWM LNB using splitters - a DVR is two tuners. You can't go beyond that.