If I wasn't egotistical, I'd make an unsolicited suggestion... Oh, wait, I am...
I assume you've got everything buffered and streamlined as much as you can with the hardware you've got. Why not serve this place up as static HTML that updates itself every 10 minutes or so. The forums, at least. That would cut down on the 'real time chat' aspect, which db forums were never really intended to be.
Add a "verify" step to the submission, so that people will edit it before it goes in, and then let them wait a few minutes for everything to update. You could even put a little 'X minutes until next update' statement somewhere so people wouldn't just sit and bang the boards checking.
At least it would take the load of the db with little or no extra expense, right? IMHO, the real strain on this place is all us nitwits banging away at the messageboard, usually when there's not been enough time for anyone to reply anyway.
Just a suggestion.