Like XP, Windows Vista has a couple of different flavors.
Win XP Home edition does NOT have IIS; Win XP pro does.
Win Vista Home edition does NOT have IIS; Vista Pro/Ultimate does.
As for location, I am pretty certain that the navigation is the same as XP (right-click my computer> Manage> Services> IIS).
Failing that, I know you can get to it from the control panel under administrative tasks> internet information services
the default root is: C:\inetpub\wwwroot