Which Calendars do I need to keep ?

Here is the situation for my wife's calendars.. MBP has Entourage and that is the primary calendar. We have that syncing to her iPhone.

We are on the latest software on every device. We had a lot of trouble gettign syncing going, but it appears we have everyting talking for moment. The result of all of this is that we have multipule claendars on the iPhone and the MBR, though only one for Entourage.

We sync via wifi and the phone backs up to iCloud.

So now we have all of these calendars and I have unchecked most of them to get rid of duplicate events and want to start deleteing the extras.

We have work, Calendar, Home, Entourage ( 2 of these ) unnamed and maybe a few more that I missed. Some of htese are under the heading of On My Mac and some under iCloud.

Which calendars do I need to keep? We only really need one calendar that is synced to all devices.

Thanks in advance for any help.