I was going to say that most firewire connectors on these recorders are input only, but I checked the manual (
http://resources.jvc.com/Resources/00/0 ... 3-001A.pdf) and behold, the rear firewire port can be IN or OUT.
I've only used the firewire port on my computer for capturing video from my Digital8 camcorder. I capture at the full DV/AVI bitrate of 25-30Mbps. Though it will only capture at 720x480 resolution. Which works for LD. Just make sure the video you've recorded to your D-VHS deck is at that resolution or lower.
Not familiar with the software you're talking about. I usually use Pinnacle Movie Studio for video capture. Though I believe that Windows Media Center will do as well (used to use Windows Movie Maker on Windows XP--I think that was absorbed into Windows Media Center for Windows 7 if not
try this.)
Theoretically though, you could just use the D-VHS deck as a bridge between the LD player and your laptop. I know my camcorder could be used as such. Just connect the LD player to the D-VHS deck and the firewire out to the Laptop and run it that way. That way you can just capture the LD video at the full DV bitrate without having to use a tape and possibly degrade the capture by doing it twice.