iphone 4s backup problems with itunes for sync w/ Outlook.

I've read several discusssion regarding the issue of the error message "iTunes could not back up the iphone "-------" because the back up was corrupt or not compatible with this iphone." I deleted the backup's from C drive and using the itunes preference section (there was no backups to delete from the preference section under devices). I'm concerned because I cannot sync my contacts or my calender from Outlook. I currently use Microsoft XP. Any ideas, is this because of the iphone 4s?