TV viewing not clear on Viewsonic 15 inch TFT monitor using external TV tuner card from Tech Com

I am using a ViewSonic TFT monitor as TV using the techcom external TV tuner card. The problem i see that the channel clarity is not very clear at all where as the tuner card shows very good TV channels on a CRT monitor. Can you please tell me what should i do to get really clear pictures (not blurred and ghost images).

Thanks,
Sandeep