I a running as a Limited account for about half year now, and I think I'm used to it, and I don't find annoying any more. After learning the tips and tricks that I needed to do so (begin a developer, so I needed ASP .NET debugging, and lots of other administrative operations too).

However, about the popup that could announce one when she has spent too much time logged in as an Administrator, I want to say that I would find that popup very annoying during the time I install things, especially when installing over Internet on a slow Internet connection (may take very long time). So I vote against it.