Of it's acceptable, I'll keep posting updates after each day I spend working on this (that won't be every day -- I can't always put aside the time).
I liked your suggestion of removing the title bars. I've kept the add thread bar (unless I can think of a sensible way of getting the same message across), but replaced the subforum/thread bars with a simpler colour coding. My assumption is that it should be clear what's what, and a short period of use would familiarise a user with the concept.
The colour scheme I am using is 3 colours selected using the adobe kuler site based on a starting colour of #3B8BF8. I then use white and black (and currently one shade in between) to produce the rest.
I will look to end with symbols. Your forum software has some features I personally don't use, such as locking threads and protecting subforums, that I might need to indicate visually somehow. My next "day" working on this will be to style the list items, the submit button and the footer. After that I will either move onto icons, or make a start on the other pages.