I'm not sure what people here use to capture video.... but I'd personally recommend a Blackmagic Decklink card. With the analog connections it'll set you back $900 USD, but they're broadcast grade cards. Of course to capture video at 8 or 10 bit uncompressed 601 you'll need at the very least a high-performance Firewire 800 raid (like the Medea G-Raid) to capture. We use Mac's in our studio, but the Decklink works with PC just as well.

...but then I just realized that if you want to come in S-Video it's not gonna work for you....