I'm almost certain that I will need only BIS but if someone could explain the difference between the two it would help. We don't have a email server system. Our server is an NT 4.0 and all email is pulled down thru microsoft outlook with multiple account. So I'm not sure how the email will be sent to the BB device (hopefully a curve from Cingular tomorrow)
BIS is for the general consumer, and BES is for when connecting to a Corporate system, for example at work - if your company runs a BlackBerry Enterprise Server (BES)...
