Access to files across user profiles

I have a new laptop with Vista.

I created several user profiles to keep my files/communications organized
for two businesses and my personal stuff. I am the only user of this computer
so I created all user profiles with ANMINISTRATOR priveledge.

I log into on (say Personal), create a document (say Word) and then try to
saed the document into one of the other profile's directory.

I get a stup MS dialog box saying that I do not have permission to do this
and it offers to save the document in the active profile's directory.

I did this all the time in XP ... why can't I do it in Vista?

Thanks for help from anyone.