[html] Change image on hover

How can I change this exact code to do the hovering effect on mouseover?

I tried following some of the other questions and answers, but I could not really follow them.

So the HTML is:

<a href="RR.html"><img src="R3.jpg" width=700 height=300 /></a>

<div>
    <a href="SSX.html"><img src="SSX.jpg" height=100 width=120 /></a>
    <a href="MPreview.html"><img src="MaxPayne3Cover.jpg" height=100 width=120 /></a>
    <a href="NC.html"><img src="NC.jpg" height=100 width=120 /></a>
    </br>
</div>

Now what I want to do is change the big size image when the mouse hovers over the small images.