Vista - Windows Mail and Office 2007 Outlook

I have a new Vista machine, with Microsoft Professional loaded. I activated
Windows Mail, which is working fine. However, when I activated the
Microsoft Professional programs, Outlook asked if I wanted it to be a
default e-mail source. I said no for the time being.

The question is: does it make sense to use Outlook's mail capabilities and
shut off the Windows Mail? If so, how would I go about activating the
Outlook mail and shutting down the Windows mail?

By the way, as I understand it, the 2007 Outlook is considerably changed
from the earlier Outlook versions, which had a bad reputation for allowing
viruses into the system. Can I assume that the new Outlook has better
e-mail security?

Thanks.

Dennis