In the first screenshot you've got the channels you don't want on the right and the ones you do on the left. It should be the other way around. Don't worry, MP does this to everyone ;-)
PS I have had problems starting with XP SP3. Start with XP SP2, do hotfixes etc. and when ok, add SP3. Ghost is your friend.
No worries, mate. MP combined with ATI video cards has driven me nuts. Been there - done that.
Logs are most likely in C:\Documents and Settings\All Users\Application Data\Team Mediaportal\Mediaportal TV Server\log and C:\Documents and Settings\All Users\Application Data\Team Mediaportal\Mediaportal\log.
Your dish is not aligned correctly or you have a bad cable/connector/LNB. Your signal quality is no good. That is your problem for sure. I'd put money on it.
Btw good on you for giving the dish a go your self, the only problem with the sat finders is they only show you how strong the signal is not how good the quality is. You might want to install the software that came with the card as it will most likley have an accurate signal QUALITY meter.