I have the following scenario:
border: solid 1px blue;
In IE (6) this displays as you would expect (with the table centered). However with Firefox (1.5) the table is left aligned.
Apparently this is due to a bug with the way FF handles CSS.
The workaround is to use this:
Don't ask me why "-moz-center" even exists - it's like they thought 'hey center doesnt work - lets make up our own version of it.. duh!
Oh well - at least it works (sort of).