uncompressed or Microsoft DV will be your best bets for use in Vegas, but that card is fairly well known for poor quality in the conversion. You'll note a lot of red in the conversions. If you're planning on doing a lot of analog to dig conversion, I'd suggest looking at a real converter vs a video card, something like the Canopus ADVC 1394. You might be able to rent a good converter box in your area.
Huffy YUV is another good choice for bringing into Vegas.