Not sure on the SD PVR, got my HD PVR a few days back and needed 2 LNB cables from Dish, one for viewing, once for recording.
The Dish also needed to be upgraded from a single LNB to dual LNB.
If you want dual-view you need a quad LNB.
There's also a converter box you need, which you can buy from the place you got the PVR, or any place where you buy DSTV Stuff (Game, Makro etc)
Easiest is the Multichoice website, they explain everything here:
http://care.dstv.com/main.aspx?ID=1723
There's also a setup guide here,
http://care.dstv.com/resourceLib/user_manuals/Install_&_Connect_your_SD_PVR.pdf
which should answer you questions...