Well, I know what it means, but what's the practical meaning of that? Out of 175MB total, there is 13 MB left. Should I start sweating? It looks to me that I can still keep on using my tab, but just try not to record a lot of video or audio, unless I know for sure that it's going to be saved on the external card. At what point (how low) would you stop to remove those memory-hogs and free up the space?