Everything from the front end of a b7 cabriolet including grill, slam panel, bonnet, bumper, wings, headlights.... on the cabriolets theres no problem with the wings (whereas on the saloon the lines on the wing wont match with the rest of the car)... Thats about it...
It is worth doing if you have reasons to (mine needs a respray so if I get the parts cheap in any colour I would get the whole car resprayed at the same time).. at other times its just worth buying a b7 as I know of cases where you don't really get your money back...
If you want to go a bit further, buy the RS4 rear quarters (with the wider arches) and rs4 front bumper.. and then that would make your car special.. i dont particularly like the b7 front end, atm i just have the b7 rear lights...