You need an ATI vidcard and then you can download digi, reg 8, hi8 and even your vcr tapes straight to your HD (if the HD is large enuff). There are several brands of vid capable vidcards but ATI is the best for the price. Go the highest vidRam on the care that you can afford for the best speeds in transfers.
Just sometimes takes a vid cable to connect odd cams. (The cards have several cables but the software might be extra) We shoot straight to the HD at times.