For many, many capture cards, Windows XP is simply required. Microsoft changed to much of the audio/video subsystem in Vista and 7 (and now 8). Honestly, for a pure work tool that's not used for the internet (i.e., no virus/malware threats), XP is easier to use, and it can be faster on older systems.
Now, as far as Canopus DV hardware is concerned, it's really old. The ADVC line is from the Pentium III generation, and it shows. You get MUCH better quality by using lossless (i.e.,
Huffyuv, Lagarith) or uncompressed video. For this reason, I suggest instead the ~2002-2006 ATI All In Wonder cards (ATI AIW), or even the ~2009 ATI 600 USB cards. To me, the Canopus DV boxes are at least a 5th choice, behind other (better) cards. It's just DV compression, which isn't great for VHS. DV is great for shooting, but fairly lousy for transferring VHS videos.
I guess it depends on your precise workflow needs. That was never mentioned.
If you have more questions, ask here.