Exchange question: How to sort by last name

[Justin01]

Okay, I'm hoping this will be an easy one. Currently, when you peruse the global directory for an address, the user list is sorted by first names, which drives me nuts. What I mean is, in Outlook, when you go to compose a new message and hit the two button, all the user accounts are listed by first name. How, in Exchange, can you change that so they're listed in alphabetical order by last name, instead of first?

I know it has to be an easy fix on the Exchange server, I just don't know where to look.

Thanks!