How to integrate POP3 accounts with Exchange

Hello, I've been using SBS2000, Exchange and Outlook for a while.
Internal email only. I now want to provide access to POP3 accounts that
are hosted and reside on an ISP. I know I can just add a POP3 account
to each user's Outlook. Can I get Exchange to go out to the ISP, open
each users POP3 account and forward the email to them? If so, would you
please point me in the right direction so I can research how to do it?

Thanks very much,

Mark Gruber