You can either:
1) Capture through DVRack, or
2) Capture through your favorite editor. Just leave the camera in 'camera' mode & connect it through the firewire.
The problem that you can run in to is that if your hard drive can not keep up with the video coming in. Then you will start getting drop outs and your footage will be garbage. I have never done it but as for quality, I guess it would depend to on not only you camera settings but your capture settings.
Since it's DV over firewire quality is the same.
With tape you may have an occasional drop out. With the comuter you have to make sure it's efficiently capturing and that you have enough space.