Hey Joe, and welcome to the Cameralabs forums! Enjoy!
To confirm, the D5100 doesn't have exposure simulation in manual mode, however I don't believe that it's included in the other modes either. Exposure simulation is a feature that Nikon's left to their pro bodies, the D3 series. It is a bit stupid that Nikon's left the feature out while Canon's including it with all of their DSLRs, but the majority of photographers probably just don't care, I really don't considering that I don't use Live View very often (unless I'm manual focusing with a fast lens, such as my 50mm f/2 which is MF only and it can be difficult to focus with such fast glass with the viewfinder). I don't think that you'll find yourself using LV very often either, the AF is slow and it's easier to use the viewfinder in bright light. But I can't speak for you, I'm just basing it on personal opinions.
By the way, if you're looking for more reviews (Cameras, lenses, accessories, etc.) check out the User Reviews
section of the forums.
Hope that I helped!