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I recommend what is called the "Pixy Fast Rollovers" which uses CSS and handles the image preload without JavaScript.
http://www.pixy.cz/blogg/clanky/cssnopreloadrollovers/update.htmlThis page above is the latest version, which includes a means to bypass an IE bug. To get step-by-step instructions, follow the link on the page to the original document.
It is super, super easy and works fantastic.
If you need help, let me know, and I will try.
Basically, you create a single image file with all the button states in it (hover, click, active, visited, etc.). Then you use offsets in CSS to have the proper button state pull up on demand.
In your case, think of the picture of the house as a giant button. Also, you might consider using hover instead of click if you don't really need the user to click.