If you are used to using the Identities feature that was in Outlook Express?
It is not available in Windows Mail. - Vista.
You can set up both email accounts in one Windows User Account, and move
messages to a created Inbox for each of you by using Message Rules, Tools
menu>message rules>Mail.
Or you could get, http://www.oehelp.com/WMIDs/Default.aspx NOT FREE, but in
this case it only costs <$15, the software was written specifically for
users just like *you*, by a MS-MVP.
You can enter multiple email accounts in WM, but it doesn't keep them
separate. All email goes into the same Inbox.
However, if you wish to send from one of the accounts, you can select it by
clicking on the From: box.