Options-->Status-->File Free gives you available memory, after OS, installed applications, caches, buffers, stored stuff, etc. Options-->Status-->File Total gives you the amount of memory not used by the OS.
I guess I used a lot of Device memory. I have over 17 1/2 MB free out of the 52 that were on my phone. I calculated that by entering the File Free/File Total here: SpeedGuide.net :: Bits/Bytes Calculator.