doing both - my company uses google apps as our e-mail host ($50/year/user with 25GB for each user, with your own domain) and Outlook as a client. You can go either pop3 or imap with the setup (we leave that up to each person). For me, I use IMAP and then set it up to keep all my e-mail on Outlook, too. Each environment has it's advantages. Outlook is great when traveling, on plane. Also, good for drag and drop,etc. Gmail is fantastic for searches.