You can do that and use Blackberry Internet Services (BIS) for the email redirection. This won't give you the same functionality as a BES, it'll only do email, not calendar, notes, contacts, all that other outlook stuff. It's free and will work with any email service with imap/pop or OWA servers. If you need BES functionality you're going to have to go the hosted exchange route. Or just do it yourself and buy an SBS server and install BES on it.