Ah! The second option (S0879) is for normal decoders. For PVRs you have to select S1959 for TV1 and S1960 for TV2. It also requires a hotfix to be installed for it to work.
Just thought I'd share that info.
PS: It looks like KB950124 is an update for Vista, so I'm not sure whether it's relevant. I'll give more feedback as I go.