I think you'll find that all they've done is add the additional buttons on the hyperlinked page "company.html"
No tricky javascript here 
You can do something similar in Fireworks by swapping slice contents from another frame but you have to be careful not to 'throw out' the layout when if your table cells expand...
If you'd rather use text for a drop down menu - there's an example of one HERE which is only a simple Dreamweaver Extension - which you can either download from the exchange or ... just rip the code from the above example 
G'Luck Misty - Let us know how you go