Okay for 1.
is it dvb-s or analogue, do you have sound? are you using just the mediaportal client or tv server and client.
first up I would check what codecs you are using for tv.
2. what are you currently using to get epg?
Okay editing here: apparently i posted between your edit
so using dvb-s the epg data is streamed with the tv signal, so if you are not getting one, you will not be getting the other. I would check the lnb settings as the dish and everything will be in the same place
As for the TV server, no you do not need it but it adds some nice features.
The fact that you can not get wintv working as well suggests to me a signal issue, which if nothing else has changed will be a lnb setting. As I haven't used dvb-s for abit as I have moved house and no longer have a dish i will leave one of the other guys to post a screenie of what these settings should be
New Zealand