That Was Easy
Scroll down a bit and look to your right: Voila! Valid XHTML. Why? Because I can... And, because everything is better with an X, I, or E at the beginning of it. :-)
Still just "transitional" instead of "strict." Strict wanted me to give up the <br clear="all" />
tags that are making my sidebars line up correctly in Netscape 4.x. I'll see if there's a workaround, but it's not a big deal -- I'm happy with transitional.