I have been using outlook for almost 20 years, but I am about to give up on it. When I switched to Mac in 2010, I loved the ease of use of the MAC OS compared to the perpetually bugged MS Windows OS. I found a few things though. While Office 2008 for Mac was prettty good, the Entourage email app was pretty poor not allowing HTML formatted email. This is not a major problem except when trying to forward HTML emails as they would appear all scrambles. As imperfect as Entourage was in email, the calendar and contacts feature were solid and syncing with iCal and Mac address book was ROCK solid. I upgraded (now it feels like a downgrade) to Outlook 2011. There is no question that the other apps (word, excel, powerpoint) are better than the 2008 Office, but Outlook 2011 is HORRIBLE due to problems syncing with iCal and address book. I was able to sync with iCal and Address book for a while, but eventually the sync services stopped syncing appointments. After hours and hours of research, I found that I could deactivate MS Sync Services in Outlook preferences, in the Library > Preferences folder I deleted the file named: com.microsoft.Outlook.SyncServicesPreferences/plist file and reset sync history in iSync. I then turn on sync services but I found that every time I did this I got duplication of any calendar event that was an "all day" event. The only way to do this would be to delete all my calendars in iCal before starting to sync again to replace all the data in iCal. The other bigger problem is that after a while, the syncing would again stop working. Sure I could reset everything again, but the effort to go through this process over and over 1-3 times per day makes this process unworkable for me. I have worked on this problem too long. The bottom line is that MS Outlook 2011 Sync Services DO NOT WORK RELIABLY!!! After almost 20 years, I must now say goodbye to Outlook. Without a reliable sync to iCal ( and then to my iPhone) Outlook calendar and address book are useless to me. Sad day, but if anyone can help me fix this problem, I will happily stay with Outlook as the calendar is much better than iCal, but without rock solid syncing, it is useless.