For unpatched E2k, your meetings will be off by one hour for the three weeks that DST transition has shifted. There is a way to mitigate that issue. Outlook is producing a similar rebasing tool to the Exchange rebasing tool, only it is client side. This tool uses MAPI to access data files directly and will work with versions of Outlook 2000 and beyond. if your customer is using one of these versions of Outlook, they can rebase their calendars without the CDO patch, They will need the Windows registry fix, but if they are not entitled to that there are some directions contained in the KB article about how to patch the registry manually.