Development I'm not doing it wrong but IE says I am

Can y'all give me a quick bit of help here? This page renders correctly in Firefox and Chromium, but not IE (7 or 8).

All my divs are all over the place. What in the name of Ron Burgundy is going on?

Please don't lecture me on my overuse of !important tags and whatnot in the css. I've been trying to get this tiny project done for people for over two months now, and when it's not a design change, it's some stupid non-compliant crap like this!

(Don't get me started on proprietary e-commerce solutions like Volusion. Grr.)

edit: I've found that it renders differently - both wrong, of course - between IE 7 and 8.
Links to screenshots:
IE7

IE8

 

Fixed it five minutes after I posted.

Thanks for your warm, fuzzy telepathic messages of empathy and encouragement.

 

lol, the hell that is internet explorer, why can't microsoft adhere to web standards properly?

 

CRAP

I didn't fix it after all. I mean, I thought I had after it looked okay in Firefox, Chromium and IE 8, but...

IT'S LOOKING EVEN WORSE IN IE 7 NOW

So anyone still care to help?

If you want to see what it looks like in IE 7 but you've upgraded to 8, just use "Compatibility View" and you'll see.

 

Firstly (have to mention this, sadly):
Tables = bad.
More DIV's less tables would be preferable.

Secondly: Avoid using -moz-* hacks as much as possible.
9/10 times there's a way around the problem without using them.

A Couple of things i noticed:
on #buttoncontainer- display:inline-block <--IE is bitchy about that.
#container - width:790px <-- IE and FF differ in how they measure width. One measures with Margins/padding, the other only with parts of them, sometimes only when they're set up correctly.
On the right thumbnails, i would wrap each item and the #shopbox div into one div. That could make things a bit better.
i.e you'd have
<div id="floaters">
<div class="itemcontainer"><div class="item">item info here</div><div class="shopbox">Shop Now!</div></div>
.
.
</div>

Nested div's are really the key to getting it right.
Try those, play around with it.

My recommendation would be to rebuild the div's one by one, style one, check in all browsers, move on. Time consuming, but it makes it easier to write lighter CSS sheets that are more cross-browser compatible.
I'm pretty sure Firehead could point out some more things here.