Thanks Jamie.
using your css, i noticed the key thing was setting a negative margin and a corresponding positive padding to each li hover class.
eg
ul#cssmw1 > li#home1:hover {
outline-style: none;
background-image: url(CSSMenuWriter/images/image.png);
border-bottom: none;
background-repeat: no-repeat;
padding-top: 150px;
margin-top: -150px;
}
When dealing with css issues, it would be better for me if I could analyse what was happening - rather than the trial and error approach I often have to use.
Anyway, it looks pretty good now, and I'm happy with it.
icing on the cake would be if the image which appears on hover was also clickable, as it stands, the image appears 'above' the navigation, but the clickable area is 'just' the text block.