Horizontal Image Menu with Mouse Over Effects

Hello

I am brand new to WordPress and this is my first post.

I am trying with very limited success to have a horiztonal image menu with hover over effects.

My test site for learning WordPress is at http://www.nisites.com/wordpress please ignore my badly made custom theme. As you can see I have started using a custom menu in a pre defined widget position to add a image menu with the help of a plugin that allows me to assign images to menu items. It wasn’t perfect but it was working. I got the horizontal part of the menu to work by displaying the div for the widget position inline in style.css which worked.

However it all looks fine under IE however in both Firefox and Chrome the menu buttons are lower down that the background menu graphic (which is built into the header graphic)as you can see if you take a look.

So my questions would be how do I either fix this or is there a simple easy to use plugin that will allow me to do what I am trying to achieve here being a nice horizontal image menu? Also if it did hover over/mouse over effects too would be fantastic.

Any help would be great please.

Thanks

Rab