Hum...given that the "soundblaster thing" is a soundcard, I really doubt it would have a video input. But I know nothing of it, just raising a point here.
About the TV cards. It depends on the quality of the cards themselves, and heavly on the connection you use. I'm only speaking from experience here, not hardware guru myself. I have a Pinnacle PCTV card to play PS2 on my PC. While the picture quality is "poor" with a composite cable, it goes to "acceptable" or "good" with s-video. Using the opensource software DScaler (which I heard about here) also helps. I've heard that there are TV cards with component input, though I've never seen one myself.
__________________
To all emulator authors and contributors: without your hard work, we'd be without many hours of enjoyment and unable to relive fond memories of childhood. Thank you.