This post on the Microsoft Office Web Apps team gives a good scenario of why and how you would use both the Microsoft Office Suite and the Microsoft Office Web Apps either through SharePoint or your Windows Live SkyDrive.

It made me think of changing my own work habits in the near future. Take a look at it and perhaps it will give you some new ideas on the way you work.

http://blogs.msdn.com/officewebapps/archive/2009/12/11/9935851.aspx