drop down menu - help needed

Hi all,
I've designed a basic website (hazelvent.com). you might laugh when you see it, long story.
I threw it up quickly with MS Publisher (all good) but customer now wants a drop down submenu from the product link and as far as I know I'll need a javascript to create this submenu. the reason I'm here is because the current product link is a jpg and the hyperlink from this jumps to the product page. all well so far but is it possible to create the submenu under the jpg using javascript using onmouseover or similar?

apologies if it sounds confusing and a messy site but I'm switching over to dreamweaver soon.