I use Pinnacle Studio which will import WMM For editing. I would have thought Vegas would too. I transferred a lot of VHS Footage to DV and the video transfer quality is not as good as the original but only by a minute amount. Of course bearing in mind that since the early days of Video tape, these days Video quality has improved to such an extent that editing virtually makes no difference to the quality.
At least you will always have the originals so you can experiment. Keeping in mind that transfer quality may not be as good as the original.
Hope this helps