I'd rather create an Exchange Mailbox for each "identity" of mine, then have all those mailboxes be accessible from Outlook, I'm perfectly happy with each mailbox having their own set of contacts and calendar.
Although this may lead to problems with PDA syncing
....And then... Outlook Web Access only supports one mailbox at a time, right?
Yep. Therefore I was suggesting to have one... You have all the stuff in one mailbox and you are fine... I'm doing this also for my four addresses.