Your problem with internet explorer is because it is an old version, I looked at your site with both FireFox and IE 7 and they both look identical. 

As for the width of the columns you have to go to the layout and click on the html button and you will have to look for code that looks like this:

<tr valign="top">
         <td width="50%">{top}{leading}<br />
         {module_position1}<br />
         </td>
         <td width="50%">{more news}<br />
         {most popular}<br />
         {module_position2}</td>

Since you are using three columns you will have three <td width="size"> but basically all you have to do is change the size to the same thing on the columns that you want changing.

One questions though, I noticed that you changed the name of the items on your page, you know the lead stories and top stories; how did you do that?

Hi Smoth,
thank you for your help, I'll try to fix following your suggestions.

About the languange:

Go to Component/i joomla news portal/ settings/ Language. Select english and press edit. You will find a string like this:

define("_TOP_STORIES","Primo piano");
define("_LEADING_STORIES","Leading stories");
define("_MORE_NEWS","More news");
define("_SECTION_LISTINGS","le notizie");
define("_SECTION_MANAGER","Section Manager");
define("_CAT_LISTINGS","Cronaca comunitaria");

Hope that this can help you.

Cheers
Sal

Remove your P tag from here:
Regards,