The only difference is that in Exchange 2007 you create Mailbox in EMC and in Exchange 2003 you creat it in ADUC. :)
Yes it should work perfectly.
Let us know if you have any questions.
Gulab | MCITP: Exchange 2010-2007 | Skype: Gulab.Mallah | Blog: www.ExchangeRanger.Blogspot.com