Question: What considerations must be made for Vista/Windows7?
ACT is not specifically "vista aware" meaning that it shouldn't trigger any UAC screens. On the other hand, it means that certain things will simply not function when access is denied. The short list of these non-functioning features is log file splitting and macro exports. That is when the game's files are in the Program Files folder, at least.
Starting ACT as administrator by right-clicking its icon will allow the shortlist of non-working features to function.