I’m not sure about the editor causing invalid XHTML. I would think this will be fixed (unless it’s not actually an issue) in Evolution 1.0, though.
Anyway, interesting site. Your layout is rather unique.
I have one small suggestion, though. I would definitely take the email address off of the Contact page. Crawlers will pick that up easily and send you lots of spam.

There’s a good chance, at least. The main advantage of SPForm and the like is so you don’t have to expose any email addresses where bots can read them.
Also, your layout is getting messed up in Opera. Actually, it shows up differently in IE8, FF 3.5 Beta, and Opera 10 Beta. Safari 3.2.2 (for Windows) shows it the same as FF. For example, on the About Us page, the text is all below the picture in Opera. It’s still looks like it’s wrapping around the picture, except the whole amount of text is just kind of shifted down.
If you don’t have the other browsers, I can upload some screenshots, but in that case I’d recommend getting some other browsers for testing.
Hope this helps.

I like what you’re doing with the site.