Syncranising outlook calendar with Iphone help

Hi, I would like to sync my Outlook calendar with my Iphone but I don't want it to mess up my calendar. I have quite a few calendar entries where I save file attachments with them like zip or image files etc. These can be large files sometimes. I don't want Itunes to strip these out when synrnising my outlook calendar with the phone and then when I reconnect my phone, it thinks these are new edited entries and replaces my original calendar. Any help or advice would be appreciated. and is there an option to do a one way sync only from outlook to my iPhone in Itunes? though I would really like to be able to update / edit my calendar on my iPhone along with tasks though I've read that Itunes won't copy across tasks from Outlook.