[Digital Jedi]

That should be much simpler, relatively speaking. If it's just to have a consistent look, and not to have any vB functionality in the non-vB areas, then it's really only a matter of styling. You would just style the theme of your non-vB pages to match the vB pages. Presuming your using another type of site building script, like WordPress or Joomla, then you just use their respective theme tools. If you're looking for deeper integration, like auto-matching your vB style or having users combined in both scripts, then you'd have to look into the different integration mods here on the site. They all do different things and have different levels of integration.