I do it because I use Microsoft Exchange for personal mail. I like having my contacts, calendar, email, and to-dos sync automatically on each computer and on th

I do it because I use Microsoft Exchange for personal mail. I like having my contacts, calendar, email, and to-dos sync automatically on each computer and on the iPhone. Plus I like how Outlook integrates a Calendar, Contacts, and Email together so it's easy to switch between them versus Gmail where I need to open a new window for calendar and contact management is a pain (though after exchange, gmail is hands down the best).