Boy Oh boy, seems today everybody and their mothers are scooping up capture cards for BetacamSP = Lots of choices out there.
Check out the DeckLink SP Component Capture Card (new product)
http://www.decklink.com/productsdecksp.asp
This card can be had for under $1,000 with Final Cut Pro component native rendering supported. Fully compatible with Mac OS X 10.2.2 or later. Universal free software codec for Mac OS X, Mac OS 9, and Windows. There is nothing else to buy, no break out box, no hidden accessories.
It captures in whopping True Uncompressed 10 bit or to save disk space it will capture in Uncompressed 8 bit.
Full analog YUV component video inputs and outputs with stereo balanced XLR analog audio inputs and outputs for direct connection to broadcast betacam tape decks. Sony compatible RS-422 serial deck control port for deck control.
Along with outputting your work out via component (for betacam) this card will also output your captured work in 10 bit or 8 bit via SDI video - perfect for outputting your project to D1, digi-beta, IMX, SX or DVCpro-50. It also has a built in DV Bridge for DV25.
Stay away from anything that doesn't offer component I/O. As component is the native betacam format.
Stay away from anything that doesn't capture or output in 4:2:2 or anything with prosumer codecs.