That patience-fu comment was more about giving up on unpaid volunteer support in well under a day.
If you've already carried through and moved on to MT you can disregard the rest of this.
I've been doing this volunteer support thing for over a year now and your site is the first time I've seen something like this. It looks fine in IE. Looks fine in Opera. Loads no style aside from the inlined stuff in FF.
Now, I do the majority of my web browsing with FF and I look at a lot of blogs. (Including all of my own). They all are quite viewable. As such, I can't agree with your initial assumption that WP blogs break in mozilla.
Do you have the live headers FF extension installed? (On my way to work so I don't have a chance to install it) I noticed when I looked at your site with Firebug it flat out doesn't see the CSS file being loaded. I wonder what the headers look like. Perhaps there's an interesting server wrinkle.