[Jack Gill] “I noticed that I see AV/C Tape Recorder/Player only when my Canopus is turned on.”
Great! Yes, the device is a “real” device so if it’s turned off Windows won’t see it. That’s great news, that means that Windows 7 can see your ADVC100.
Next, with the ADVC100 turned on, in Vegas Pro 12 when you go to File | Capture Video… to capture your tapes, do you see this dialog box pop up and do your select DV? (you should)

That should bring up the VidCap program that captures from DV tape.

And you should see the window above. Do you get that?
~jr
http://www.johnrofrano.com
http://www.vasstsoftware.com