Issues - differences in IE & Firefox - help needed

Hi all - I originally posted in the Stylesheet forum here (thanks to Kuroi for the initial help):
http://www.zen-cart.com/forum/showthread.php?t=36407
and in the Page Layout forum (no replies as yet) here:
http://www.zen-cart.com/forum/showthread.php?t=36432

I've attached a screenshot trying to illustrate my problems. I have things looking good in Firefox (thank goodness for Web Developer tools!) but I have problems in IE.

I need help eliminating the gap below the logo image (I think my current workaround of a negative margin on the navbar is not optimal) I did try eliminating <br class="clearBoth" /> from tpl_header but it resulted in my nav bar getting pulled up into the header section.

I also need help trying to figure out spacing on the side columns - I have currently set the height of the breadcrumb and columnWrapper margin using ems in the CSS...and again, it looks clean and crisp in Firefox, but there is a jog (albeit a small one) in IE.

Any and all suggestions and guidance are appreciated.

Thanks!