Hiding/Showing a Div with JavaScript.

[MrApples]

What action do I need to use to hide or show a div, and everything it contains. I know that it needs a seperate ID, and how to call the function, but I need to know the action.

My current way of going about this(without the action of course).

<script type="text/javascript">
hcur=0

function hidelast(){
switch(hcur){
case 0:
    hide div0
    break
case 1:
    hide div1
    break}
}

function header_main(){
if ( hcur!=0 ){
    hidelast()
    hcur = 0
    show div0}
}

function header_diff1(){
if ( hcur!=1 ){
    hidelast()
    hcur = 1
    show div1}
}
</script>

...

<div id="div0">
    <a href="url"><img onmouseover="header_main()"></a>
</div>
<div id="div1">
    <a href="url"><img onmouseover="header_diff1()"></a>
</div>

I'm asking for just the action on hiding/showing a div, but if anyone can see something obvious wrong with my logic please, point that out too, this is my first time writing JS. This is intended for about 5 divs.