I haven't had any issues breaking follow but I have 3 WoW folders on 2 separate drives. I only have 4GB RAM, but do have Vista64.

C:\Main
C:\alt\2 & 3
D:\4 & 5

This minimizes the HD churning which I've found to be the biggest hindrance to keeping follow. All 5 windows are visible on 2 screens, none minimized.