I am working on a new front page for my website, w3.schylling.com

The idea was to have 10 catagory images on the page and when you mouseover the image you get a drop down that tells you the subcatagories.

Here is my example page: w3.schylling.com/test26.html

On this example page you can see the 10 different image icons I have set up.
What i would like to achieve is when a customer rolls their mouse over one of the images a drop down shows up listing the sub-catagories. The sub catagories can thne be clicked on to go to that particular page.

What is the best method to do this? Flash, CSS????

Any help would be greatly appreciated.