Help from validator?

Hello,

It seems, the validator is a good thing to create valide (x)html code.  
But does the validator really say how the most used Browser (Internet 
Explorer) behaves if my code is valide?

In my case it's the website http://www.web-for-you.com/ which should 
look like http://www.web-for-you.com/screenshots/web-for-you.png but it 
does not with IE.  Mozilla and Galeon show it correctly.

The page is really valide 
(http://validator.w3.org/check?uri=http%3A%2F%2Fwww.web-for-you.com) as 
also the stylesheet of this page 
(http://jigsaw.w3.org/css-validator/validator?uri=http%3A%2F%2Fwww.web-for-you.com%2Fstyles.css&warning=1&profile=css2).  
But it is not useable right now.

What do I have to do now?  And whats the validator for?  Seems the 
validator does not really help in web design.

Martin