By one column has to be root i mean that...

The hierarchy goes as follows///
One of the column is Manufacturer... it would have many types of devices.. and then each type of device would have further substypes... for eg....

Manufacturer-----Device--------- Product
---------------------------------------------------------
HP-----------------Printer------------Inkjet
----------------------------------------Laser
--------------------Camera-----------Digital
----------------------------------------Analog

Cannon-------------Printer------------Inkjet
----------------------------------------Laser
---------------------Camera-----------Digital
----------------------------------------Analog

Other----------------Printer------------Inkjet
------------------------------------------Laser
----------------------Camera-----------Digital
------------------------------------------Analog

So here Manufacturer column is root so when user selected an item from Manufacturer column then the Devices column is branched and so on...
It is similar to MAC Finder window.....
I need to create a Tree Model and i am totally blank on how to proceed.......

Please help
GK