The written english part is just one of the phases of TOEFL.
It includes reading comprehension, listening comprehension, some grammar and the essay.
It's based on 300 points maximum, the essay is based on 6.0. There's no pass or fail. They just give you your score and each school has its minimum score requirement. Depending on what you're aiming for you need more or less. Most schools require 230 or more. Some school even go as far as requiring a minimun total score, plus a mininum of 5.0 on the essay.
I took it over a year ago, so I don't remember the exact parts of it too well.
Hope this helps.
EDIT:
The Test of Spoken English right now is a separate test, but in 2005 they will include it with the TOEFL. This part involves a conversation with a test administrator.
The Test of Written English used to be separate too, but they mixed it some time ago.
This way is better, 'cause is cheaper and more practical, just one test measures it all.
