CSVDE

CSVDE is a great tool included with Windows 2003 Server that allows you to import accounts using a comma-separated values (CSV) file.

Exchange 2003 mailboxes can also be created with the import. Use the export function first to understand what fields and values to use. Here are the fields I need:

objectClass (always "user")
DN
givenName
initials
sn
displayName
sAMAccountName
userPrincipalName
userAccountControl (always 514)
msExchHomeServerName
homeMDB
mailNickname
mail
mDBUseDefaults (always "TRUE")

Here are some sites with more information:

How can I create a large number of users for testing purposes?
Brief but comprehensive guide to several bulk import options from Petri.co.il.

Introduction to CSVDE
Check out the Excel tips in the Advanced Import section from ComputerPerformance.co.uk.

These accounts will be disabled. CSVDE can't do passwords - they should be set and the accounts enabled with a script I'll post soon.