Ultimate : standard edition Ultimate E : without Internet Explorer Ultimate N : without Media Player the standard edition is the one to go with. The other 2 editions won't get activated since we do not have leaked OEM SLP keys for those editions. also, be aware that E edition has been canceled, it won't be sold.
Ultimate : standard edition Ultimate E : without Internet Explorer Ultimate N : without Internet Explorer ,Media Player and associated Programs ,(ie:no movie maker etc.) and it can be activated by replacing some key files from Ultimate standard, there is a small script to automate this process in this forum (do a search) its a kind of frankenbiuld ,with no associated problems ,OS will still show up as (E) or (N) and updates work (for the time being.