Windows 7 User Submissions

I have two windows 7 computers at home shared amongst 4 people

by dad
(long island, ny)

I have two windows 7 computers at home shared amongst 4 people.
Each person has their own user account on both computers.

User names are Mom,Dad,Cindy and Johnny

i would like each user to share their own mydocuments folders only with themselves on each computer. This way anyone can sit down on either computer that is available and access their own documents across the Home Lan.

Homegroups did't do the trick because everyone can see everyone's stuff and the kids are teenagers (you see.)

what would be the easiest way to set this kind of thing