I see what you're saying, Scot-Bot, and that could be a problem in some circumstances. In this case, however, I think it will be OK--because the content that's being replaced is entirely invisible to non-JS users as it's inside a DHTML script. So I'll just use the <noscript> tag to write a nav table, which will appear in approximately the same location as the DHTML content would.

I haven't done this just yet because I am a little stumped as to how to fit all the most important navigational items--there are probably 10 to 15--in one regular HTML table. I'm still scratching my head over that one. I suppose that providing some alternate navigation is better than providing none, but I really want to do it the right way since it's an ecommerce site, and if folks can't find what they want, then those 6% will still be lost potential customers.