No, it is not "lost" space, as I explained to you this is used by the file system for management/file allocation table/etc... Windows 7 presents you the real information, the space that will be available after formatting if you use NTFS. Use a different OS or file system if you don't like it, but other file systems are likely to do the same, I don't know if the space percentage used for management is different or better for Mac OS or Linux/Unix though.
All I know is that for NTFS, 236GB is perfectly normal for a 256GB drive. I have a 1 TB HDD at home and after format I only have 920 GB left or something.
let me see if i get this. the SSD/HDD uses this space to move around the information every time i write something to it? like the hallway in a storage room? does the analogy apply? if not please enlighten me