This is a question we got in last week and we were able to point the client to an open source program to allow them to have an easy to use program that was not Microsoft based.
Eudora Mail
Windows Mail
http://www.microsoft.com/windows/windows-vista/features/mail.aspx
Thunderbird
http://www.mozillamessaging.com/en-US/thunderbird/
We would recommend using Thunderbird as it has great plug-in features that the other are only catching onto now, and it easily allows you to configure separate in-boxes for different emails. A common question into our offices.
