FYI - I've been working the last 2 weeks on upgrading V to Drupal 7. I have worked out most of what's required. The site I'm using to test is installed in a virtual Ubuntu machine on my laptop but I'll be able to replicate it on the server shortly.
I've got a number of issues to straighten out still, but that number is shrinking by the hour.
When it comes time to perform the actual conversion - I'll have to disable V for most of a day.
I'll also make a backup of everything as I go along, in case there's a need to abort and revert to the current site.