Does anyone else use one of these tuner cards?

I have been playing aorund on my system, and have the following, AMD X2 Duel Core 3800, 2gig DDR RAM, Fusion HDTV DVB-T plus tv tuner card, 7800GT Graphics...

I have an old Sky UHF aerial hooked into my card, I live in Foxton just out of Palmerston North, used PowerDVD7 ultra, now i use mediaportal....

Have managed to get tv2 and tv1....not very successfully thru mediportal, problem i get is i get a slight picture, usually sound but picture freezes, am using windows XP also....

thanks