Put it in user mode and then head on over to A V F O R U M S .com and look at the plasma panel forum -- 8G owners thread.
try the settings in the first post and play around with them for your tastes -- but the minimum I'd do is chuck it in movie -- but USER is best as it allows you to play around with your own settings per input.
I've had mine for a couple of weeks now and got to say I'm blown away with the picture that even Freeview produces. I was really worried I was going to miss what was a top of the range (at the time Sony CRT) but the pioneer puts it too shame. Even on a 42" screen the picture processing it has is awesome and definately gives a much cleaner and noise free picture.
If you want me to copy down what I'm using let me know and I'll post them back here.