I have a four server environment. One SBS 2003 and three 2003 Standard servers. I am converting to a virtualized 2008 Enterprise server environment. I want to virtualize 2008 then reinstall the applications. I plan on migrating the SBS/ Exchange server last. One of the 2003 STD servers is a Professional Express BES server. I would like to put up a new Blackberry Enterprise Server Express for Exchange hook it to the old 2003 Exchange, eventually migrate from Exchange 2003 Spack2 to Exchange 2010 and finally modify the BES config to point to the new Exchange BES server. Will I run into any issues switching the BES config from Exchange 2003 to 2010? Do you have any experience with this?