Can a folder be shared without being administrator?

Greetings,

in our AD2003 domain, we are now installing Vista computers for our users.
The users are all in the Power User group.
We usually created a folder for each person on each computer (ex: C:\JDOE)
which then becomes the Documents folders.

Now, problem is, users can't share folders inside that C:\JDOE (or anywhere
else it seems), without being computer administrators. When they try to
share, an elevated privilege window pops up, asking for a user and password
of someone with admin authority.

I checked, and they have full control on the folders they try to share.
I also read somewhere that people wanting to share folders, must be in a
"group" which allows them to share folders. Is this so? Is there a group
policy which can enable sharing by less powerful groups?

Thanks in advance.

Rodrigo Monteiro