I have noticed that it’s sometimes better not to define a width for a td because the IE and the FF interprete it differently. This might help if you try to arrange a sidebar and wonder why the IE is displaying it in another position.

Sometimes the IE will expand a td or any other box without a reason.
This is due to a small bug. If it’s pure text then try using “word-wrap: break-word” inside your css file. To get it working for graphics and other things use style=”overflow:hidden”. Note that this might clip some of the data inside the td/box.

Source:Adobe.com

If you got an image inside a td using the img html tag and you want to center the table in firefox it will sometimes not do it properly.
It helps to add style=”text-align:center;width:xxx;” to the img tag.