As Sparky101 has mentioned the upload speed is the actual problem here which effects the quality.
I have the slingbox connected into my Humax PVR and it works really well in the house or outside using a wireless laptop, but it's a different story 5, 10, 50 miles away because of the upload speed. I have ADSL MAX (448kbps upstream). On a normal PC it's OK if there are no other downloads taking place, unless you keep the screen size small. I watch TV on my Nokia N95 using 3.5G, and to be fair, it's good enough for watching anything.
It all depends on what your upload speed is where the slingbox is connected. The slingbox has to wired (not wireless), else it would be too slow. Try streaming a movie over a wireless. It worsens over great distances.
In terms of connection, my aerial cable is plugged to my PVR (which has it's own tuner), from there I have a cable that plugs into the slingbox (so the channels are coming from the PVR).
The slingbox is an exact mirror of whatever it is plugged into. It has two IR cables that go from the Slingbox to the device you are attaching too. You place them over the IR sensor. So if you plug it into a sky box or TV or PVR, then where ever you are in the world, when you connect to the slingbox over IP, you assume the role of (remote control) of the sky box or TV or PVR in my case at that moment in time.
Example using Slingbox Classic (single device):
If my wife is watching a recorded show on the PVR and I happen to switch on my Sling Client, then I see exactly what she is looking at. If I pause the recording, it pauses on her end (and she gets ****** off), but lets say my wife is watching channel 5 on TV and I switch on my Sling Client and want to watch Channel 3, then I can without any problem, because the TV has a separate tuner to the PVR, but if later she wants to watch a recorded show on the PVR, she would have to switch off the recording I am watching, and effectively take over the PVR. I could say "up yours" and leave the sling client or be forced to watch whatever she is watching....

(this happens on many occassions).
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