Gecko's stubborn legend element

The upper and lower forms are presented identically in IE6 and Opera 9. However, the upper form is presented differently in Gecko based browsers. I would like to avoid the extraneous div elements in the lower form. Any suggestions as to how the upper form can be styled in Gecko?

Set OneContent and inputs for set one
Set TwoContent and inputs for set two
Set ThreeContent and inputs for set three
Set OneContent and inputs for set one
Set TwoContent and inputs for set two
Set ThreeContent and inputs for set three