customize drop-down box

[Art]

Is there a way to use Data Validation to create an in-cell drop-down box from
a range of cells...but before displaying that list in the drop-down box, can
you

(1) remove duplicate values (e.g., names)
(2) alphabetize the list

I have a list of instructors I want to automatically appear in the drop-down
box, but the range the drop-down box draws from contains duplicate instructor
names, and the names are not alphabetized.

Thanks!

 

[Art]

I'm using Excel 2007.