Similar product to entourage project centre that will sync with ical

I have been using entourage, however, would like to just use ical. I like the project organisation in entourage and was hoping to find a similar mac product, something where I can bring tasks, notes, emails, files etc together based on projects. Nothing that mac offers in its iworks, ilife or mail program compares in this feature. I want software that is not too complicated but something that could integrate well with ical etc.

Any referrals would be appreciated. Thanks.
Treezy