DAAD Conversion
I've got a Sony DVMC-DA1 (DVMC-DA2 is the current model), all it does is converts analog to firewire and back. It's great, but it costs almost as much as a cheap MiniDV camcorder. When I bought it, the camera I was using (Canon Optura) did not have Analog inputs. I've since replaced that camera with a GL1 which has analog in so it's now used mainly for Final Cut Pro previewing and for output to an SVHS VCR. A couple other companies are making converters now as well, I think Formac is one of them.
When I've got VHS/SVHS source material to capture, I dub it to MiniDV via my camera's analog inputs and then capture from the MiniDV copy via firewire. This allows frame-acurate captures (as acurate as MiniDV can be) and batch capturing. I'm not sure what application you're using though - if it's iMovie, batch capturing is not an option I don't believe. (I could be wrong, I rarely ever use iMovie)