I've been using Iframes for a few years, they are simple to set up and you get a lot of control on your layout design.
Shame to hear WC3 XHTML are dropping it, I hope future IE releases will still support Iframes. My site uses them, I also use them for a gallery in my 3d and vr games section
www.richard1973.co.uk (though site is down today, well it was earlier

)