First time at Valid HTML and CSS and Tableless Web Design... NEED HELP!

Hi everyone, I need help! :beam:

I’m making a Web Design right now and I need some opinions of pro’s (read: people with more skill than me, aka most people). This is my first time I’ve made a web design where I’m going for more than just valid HTML and CSS but also a completely table-less design with no other ‘messy’ things like using absolute positions and (I’m not sure of the term for it) ‘fluid’ design.
I’m slowly getting there but I’ve run into some problems which have got me stuck. Basically my design has two problems which show on 2 different browser.
The first problem is that my menu isn’t shrinking correctly in IE. To see what I mean, click on the link below and open the page in IE then try shrinking the window smaller than 800xsomething. The second problem is that my main body of text isn’t where it should be in Firefox. This problem is VERY visible. Just open the link below in FF and you’ll see what I mean.

I’ve be at these two little problems for about 24hrs now and I still haven’t found a solution. :hangover:

All the CSS and HTML are in the one page, just ‘view source’-it.
Any and all help and feedback on the design would be greatly appreciated.

Link to the Design.