Wirelessly posted (Nokia E71: Opera/9.50 (J2ME/MIDP; Opera Mini/4.1.11355/542; U; en))
You should be able to setup Microsoft Exchange on your iPhone quite easily. Just tap on the Exchange logo and provide the wizard with your e-mail address, username, password and server address. The server address should be identical to the URL you're currently using for accessing Outlook Web Access (except maybe the word 'owa').