V2 profiles were introduced with Windows Vista to allow isolation between XP and newer operating systems. "Managing user data is a critical part of business environment. Today's customers use a combination of desktop, laptops, and terminal services, challenging administrators to make user data available in a consistent way. This guide covers using these new features to introduce Vista in a XP environment. If you haven't done so already, make sure to review Managing Roaming User Data Deployment Guide (Online / Offline).
If you've a mixture of V1 and V2 profiles and are planning an ADMT 3.2 migration, make sure you review this updated planning guide: ADMT 3.2 and Managing Users, Groups, and User Profiles - This covers planning and deployment steps to make sure these profiles migrate correctly.