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To answer your first question, you will need another satellite coaxial cable run from your dish to your PC to hook up the DVB-S2 card. Depending on your Sky receiver, you may have one or two cable runs from your dish at present. If your dish has a single feed LNB (one cable from the dish), you will need to get this replaced with a dual LNB to provide the additional connection for your PC. However, if your dish already has a dual LNB, which would be the case if you have a Sky+ receiver, you will need to get this replaced with a quad LNB to cater for the additional cable to your PC. Assuming your dish is a regular Sky dish, you will need to make sure that the quad LNB you get is Sky mini dish compatible or you get a Sky mini dish fitting to allow the use of a standard quad LNB.
If you are mainly interested in watching the BBC HD channel and the freely available channels (similar to those on UK's Freeview service) a DVB-S2 card would be sufficient for your PC.
Using the DVB-S2 card to watch Sky or Sky HD is more tricky and the cost of the extra components required is quite expensive (~Â£135 or â‚¬200 on top of the DVB-S2 card), since Sky only officially supports its Sky boxes. Sky uses a proprietary encryption system Videoguard (NDS), which is not available as a CAM, at least without emulation. If you are seriously interested in watching Sky HD on your PC, first, you will need to upgrade to a Sky HD subscription and HD Digibox. For an a regular Sky subscription, the following requirements still apply, but you'll just not be able to watch their HD programming unless you upgrade:
- A DVB-S2 card with a CI slot
- Dragon CAM (capable of emulating the NDS encryption system to allow the use of your subscription card.)
- Dragon loader card (usually supplied with the Dragon CAM, but double-check with the store to be sure) to load the emulation firmware on to the Dragon CAM.
- Programmer for the loader card (such as the Dynamite USB programmer) to place the firmware on the loader card.
To summarise the process to give an idea of how this works, the first step is to set up the DVB-S2 with the PC, install the DVB software and do a channel scan. Next, install the programmer and load at least version 3.53 of the Dragon software onto the Dragon loader card. Then place the loader card into the CAM and place the CAM into the DVB-S2's CI slot. Go into the CAM menu from the satellite tuner software and select 'Dragon load' and allow the update process to take place. Once this has complete, remove the CAM and the loaer card from the CAM. Next, insert the CAM and then your Sky subscription card into the CAM. From the CAM menu, set the NDS serial number to the serial number of your Sky receiver that the viewing card came from. If all goes well, you should be able to watch the Sky service from your PC along with Sky HD if you have a Sky HD subscription.
As I mentioned, Sky does not officially support the viewing of its services in any receiver other than Sky HD receiver, so Sky can at anytime upgrade its encryption system in an attempt to restrict viewing to its own Sky receivers, so unless you really want to watch Sky through your PC, I would recommend having a Sky HD box installed in your bedroom for the HD TV.
Note that it is not possible to watch Sky in your Sky receiver and on the PC at the same time due to the one viewing card. Going by what I read, you will also need to place your viewing card back in the Sky receiver at least once a month to prevent it from becoming deactivated.
Note that the TV Link feature only allows viewing in another room through a TV coaxial connection, not through a DVB-S or DVB-S2 card.