Show-Hide a div tag with onLoad or something similar

You can use the Show-Hide Elements Behaviour onLoad perfectly well on an image, but it doesn’t work on a div tag.

What I need is for the Div tag to be intially hidden when the page loads, but once it is rolled over (MouseOver) it appears again.

Stuff like <noscript></noscript> around the div, or setting display to none etc doesn’t work because it then doesn’t register the other behaviours. Any suggestions?