One of the most common questions we get is how does Outlook 2003 compare with previous versions of Outlook.  Also, how does Outlook Web Access 2003 compare with OWA 2000?  Well, now there is a real detailed look at the benefits of the newer versions.  It even goes as far as to show the differences between Outlook 2003 with cached mode on or off, RPC over HTTPS, OWA Premium .vs OWA Basic, and using Forms based authentication.

I think you will find the results interesting.

http://www.microsoft.com/exchange/techinfo/outlook/CliNetTraf.asp