Keep in mind the original video is all of 480 lines which you'll see 400 on most TVs and when people put such on a computer, ALL the raggedness will show up. Why? We usually run it full screen and that's a 4 times (or more) zoom in. Computer monitors are also adept at showing all the defects.
In short, you may be looking at the real picture and not a loss of quality from DV to PC.
i have a panasonic nvgs15, and have copied my dv cassette thro the firewire port using windows movie maker(in the highest resolution possible).BUT i am not satisfied with the quality of the video created on the comp. Do you think using a better programme will help.