I'm sure someone has run across this.
I am using twoColFixLtHdr template.
When I place a table in the mainContent div it bounces it down past the sidebar1 div in IE6.
Short answer: Make table smaller, or make your page wider.
Float drop issues most often occur when a container width (including the body) is insufficiently wide enough to accommodate the float and content that follows it side-by-side.
More on Float Drop and how to avoid it.
That was it. I didn't think it was too wide - and it worked in all the other browsers but it was about 2px too wide.
I forgot to zero the table border and padding - it defaulted to more than zero in IE 6 I guess.