Compatible html coding for IE and Firefox

Hi,

I’m having trouble designing a site to display properly in both IE and Firefox.

The company that i work for has a policy that we make sure that sites display properly in IE first and foremost.

However, as hard as i try i cannot get the current site that i am working on to display properly in both IE and Firefox. Their isn’t major problems just lining things up etc.

I generally use tables for laying out the site.

i was wondering if anyone knows of a list of incompatiblities between the 2 browsers? or have i fallen into the trap of lazy coding in IE?

any links or tools that could help me would be gratly appreciated.

many thanks