Apple just released version 3.1 of the iCloud Control panel. This panel is fully compatible with Windows 8.1.
The control panel is necessary should you want to be fully connected to your iCloud environment syncing calendars, contacts, reminders and mail transparently in Windows say under Outlook 2013.
Interestingly, it is not possible to connect and sync Outlook 2011 for the Mac. Microsoft has failed to provide Caldav and Cardav compatibility. Instead, they used the old sync services to provide sync. Sync services has been fully dismantled in Mavericks.
It’s hard to know what Microsoft is thinking anymore. They had plenty of time to prepare Outlook for Caldav and Cardav support. It is expected that this support will be in the next version of Outlook for the Mac but then again until it’s there we won’t know.