Hi I've this site with marketpress plugin in wordpress.

And I have to show the items products in horizontal mode like this.

But does't work when convey more of 6 products the items indexed by one column

You will have to set display: -moz-inline-block; display:inline-block; zoom:1; *display:inline; vertical-align:top; for the product container divs inside your CSS file.

EDIT: Read this too: http://blog.mozilla.com/webdev/2009/02/20/cross-browser-inline-block/