watching multiple exchange email accounts -send from each?

I am using Outlook 2003 SP2 and exchange small business server 2003 standard.
I have several email accounts coming into my outlook and, although I have
set up sep. in-box-type folders so they will group coming in, I cannot figure
out how to initiate an email from another one of these accounts (it always
looks like it is coming from my main user account). In my previous vs I
could just choose which account I wanted to send from - but this doesn't seem
to be an option anymore.

When I look at email accounts, it looks like I just have 1 exchange account.
I have added the other email addresses I watch under the user email account
properties on the server and they are definately coming in. These other
email accounts don't actually have other USER profiles in Exchange associate
with them.
Help?