Hi,
If you are running BES 4.1 you should just upgrade to the latest service pack (these new updates include the DST database upgrade) and ensure all the MS Exchange Patches are installed on the mail server and BES. Please review the details within the link Supabrudda provided above as certain device firmware will require patching if present within you BlackBerry network.
How to prepare the BES for Microsoft Exchange to support DST changes in 2008
Thanks,
Gary