IE not playing ball

[blueuniverse]

Firefox is displaying my site absolutely perfectly but on inspection in IE I've realised how badly it's been reacting. There are about 5/6 errors I've come across on the site so far but I'm not quite sure how to resolve them.

The site before I start is here

Error number 1 - Margin or padding at top

Internet explorer is adding some kind of margin or padding at the top. Firefox isn't doing this at all and basically I can't see why IE is. It's quite easy to see if you look in IE. The table should basically be tight to the top as it is in firefox.
Error number 2 - Adverts don't line up

At the top I have an advert space with the ads needing to line up against the background image as they do in firefox. In IE you can see that they're just nudged down a bit ruining the alignment.

Error number 3 - Bottom bar doesn't extend

The bar at the very bottom with the privacy statement, home etc. links doesn't extend the full length of the site. (I think this might be related to the next problem) In Firefox it extends fully just fine.

Error 4 - On topic page

On this page for example. It all lines up Ok in firefox but in IE the post content shifts over to the right without the top navbar.

Error 5 - Big gap at the side

I have a feeling this may be the cause of all or most of the problems. There is a gap larger than the left hand side gap on the right. These should both be the same as in firefox.

General problem

There is also a little gap at the bottom in both IE and firefox which I'd like to remove.

I can provide screenshots for all the problems if you wish. I'd also like it if somebody could tell me whether it comes up OK in Opera.

Sorry for having so many problems, I don't mind if you can just respond with a solution to one. If you have any queries don't hesitate to ask.

- ed