Pay careful attention to this advice! I've been using gmail for several years as a repository for my Exchange Outlook email as well as some other little used POP3 accounts. Its threading of conversations takes some getting used to and is sometimes problematic compared to Outlook, but it makes up for all of that with its WONDERFUL search capabilities that Outlook lacks. It also avoids the maddening problems of limits on the archival capacity of Outlook. I have every email I've ever received and almost every one I've sent over the last five years on gmail and I currently use only about 20% of the free space my account allows. All that without ever using gmail as my primary email account.
Now that I have the Droid, I find gmail even more useful. And with the simple synch features of gmail calendar with my outlook calendar there are no lost appointments.
I spent several frustrating years with a Windows Mobile phone primarily to integrate my desktop in my home office with my phone. Within a week I was able to achieve all that integration using gmail and google calendar in a device that offers infinitely more other capabilities.
And the best part was that I did it all without once having to deal with my company's IT department and their balky exchange server. I still get all my exchange email on outlook and calendar notifications from the same source. But they typically come in five to fifteen minutes after google has already updated and my phone has notified me.
