Here's how to turn a black and white image to a colored one when you put the mouse over it. You start with a colored pic, although it will look black and white at the beginning on your site.  The pic I've chosen is called "gall9.jpg"

Put this code in the body of your site, substituting the name of your image for mine where it says <img src>:

<img src="gall9.jpg" style="filter:progid:DXImageTransform.Microsoft.BasicImage(grayscale=1)" onmouseover="this.style.filter='progid:DXImageTransform.Microsoft.BasicImage(grayscale=0)'" onmouseout="this.style.filter='progid:DXImageTransform.Microsoft.BasicImage(grayscale=1)'">