Basic and Windows Integrated Info Ver 6.0

Using IIS in relationship to OWA users can send their network user ID and
password via Basic Authentication. I am also using Entrust SSL Certificates
for added security. Sharepoint has been introduced and we are allowing user
to access their Calendars via an OWA link. Users also sign into the
SharePoint space with their network user ID and password. Sharepoint is
using Kerberos. The issue is that IIS is set for Basic and SharePoint
requires Integrated Windows Authentication otherwise the user must sign in
to the OWA client within SharePoint although they are signed into SharePoint
with the same credentials. My question is: Can Basic and Integrated Windows
authentication be selected in IIS and, if so, will it still work for OWA
users not logged into SharePoint?

Thanks
Rory