This thread should have been posted in
Peripherals.
I have the
Miglia DVR PCI tuner/capture card. It costs about
$150 at OWC, sometimes less from Amazon. It has RCA (and S) video-in jacks, as well as a 1/8" audio-in jack. Add some adapters from Radio Shack and you have all three RCA-in jacks.
The video capture quality is decent but not perfect. The better
FireWire solutions cost twice as much. The better solutions add hardware DV encoding, which offloads the CPU quite a bit. But you'll likely want to convert to higher compression formats later, unless you have unlimited HD space handy.
My own shopping didn't turn up any hardware MPEG-2 encoding cards for Mac. At least, none in the consumer price range, I didn't look for $1K+ solutions.