Hi Guys & girls of course i am in need of help before i go out and spend more money on another tv card ! i am new to this so please forgive me if i sound stupid

i am currently using a Pinnacle PCTV rave pci card to watch Digital TV through a freeview set top box (im English) i have an adapter from scart to composite and svideo into the back of my tv card and i cant seem to get a decent picture, its worse through Svideo than composite.Is it anything to do with my graphics i have intel onboard AGP 64mg extreme graphics. ive reinstalled the software and drivers for the tv card and the cables are high quality gold plated. im considering buying a new tv card
Why these naff pictures through Svideo?