drop downs

Hi there,

I'm looking (if possible) to create a drop down based on the outcome of another drop down.

for example....

Is it possible to first have a drop down with 3 items on the list such as roof, window and door.

Then once the selection is made, would it be possible to populate another drop down with a list associated to the first choice (so if roof was selected, the next drop down would contain the items thatched, tiled etc)

http://img143.imageshack.us/img143/6742/exceluq5.jpg

Thanks in advance,