SP5 will work with Exchange 2003. All BES versions work with Exchange, only 2007 requires certification as it does not work the same as 2003 and earlier. You can jump right to SP5, all SP's are cumulative.
like anything MSFT when they decide to do a major change, they make everyone jump through hoops for their software to work with it (Vista anyone?) BES 4.1.5 is currently running on Exchange 2003 in my house with no issues
like anything MSFT when they decide to do a major change, they make everyone jump through hoops for their software to work with it (Vista anyone?) BES 4.1.5 is currently running on Exchange 2003 in my house with no issues