Apparently I was facing two defects in IE. Both centre around IE's very broken float implementation.
The first bug is "The IE Three Pixel Text-Jog", and the second is the "Peek-a-boo IE6 bug". Thankfully there is a sane solution to both problems, so I can work around the broken behaviour of IE6 without messing up the correct behaviour of Mozilla, Opera or any other standard compliant browser.
I also discovered the