couple of points to mention when going from minidv to whatever...
ive seen a lot of people skip deinterlacing, generally when i mention it i hear "huh? whats deinterlacing?"
http://bitav.net/interlaced.jpg
interlaced video looks like the sample jpg. when you play back on tv/cam/dvd the hardware deinterlaces the video, if you encode the wmv from interlaced video it will look shitty.
i dont use vegas so i wont be any help there. my personal preference is to capture from minidv to uncompressed avi then deinterlace and resize in virtualdub.
your source is probably 720x480, when you add the deinterlace filter you will want to resize to 640x480 and i like the bilinear over bicubic filter when shrinking... bicubic if increasing the rez.
you can export the resized/deinterlaced video to uncompressed avi (will be bigger than the avi you have captured) the captured avi you have is most likely a DV-AVI and not uncompressed avi. you could also export to unrestrained divx/xvid or huffy.
edit: you can also add your watermark in virtualdub during this step