IE CSS problems

I recently put up a new theme on a dev site but I’m having some problems resolving a few css issues in IE. IE7 is pretty much ok, but IE6 is really bad, and cause i’m on vista now, i can’t even see what needs changing, just been told there are problems.

if you look in firefox, everything is fine https://dev.dearcinema.com/

In IE 7 i can’t get the current page highlighting to extend to the bottom of the menu bar, and in IE 6 apparently its completely misaligned and the rotating tabs are jumping down lines. Pretty sure its to do with margins!

I really need your guys help on this one to sort this out.