Welcome to the standards work that we all have to do.
There are various effects that can appear in tables. For example, F'fox adds its own row height padding (as I have found) and does not like non-breaking spaces in rows at all.
However, when I viewed your site, I saw primarily columns - if you have rows at all, they must be split across the columns, as nothing suggests row alignment. It is your last column (fourth I would guess, without looking through the code) that is suffering.
You should start by looking at object positioning - top, left, etc. - and work from there.