There is a calendar sync application that will sync your outlook with a google account... Then once things are synced to a google account its cake. That may be an option to you unless you're like the small number of paranoid's and/or zealots that don't want to trust a company w/ their data.

 

Go to your Google Calendar, click settings on top right, then click sync with Oulook.

It is an automated process that runs through user defined times and works very well.

 

You can also look at Google Apps Standard Edition for an office of 50 people or less if you are looking into wanting to share info.