Domain Controller, User folders and Permissions

Hello,

I just installed fresh copy of windows 2003 server R2 on my server. I created Domain on same server. This is the only machine which is a DC in my small network. I created 2 users in server by going to active directory users and computers, and then I registered two windows XP systems to this domain controller.

Now I want to create folders in DC such that two domain users, user X can only see and can only read/write/delete contents of his folder and user Y can only perform all such tasks with his folder only. X should not be able to see Y's folder or its contents.

I am not really good in folder security and permission settings specially in Domain environment. Please give me steps to perform this, In case somebody thinks that what I am thinking is not a practical approach Please feel free to advise me, I want to run this setup/settings in a small clinic environment.

My other question is if there are two computers A and computer B , The two created users can log in to any one of them just by using their domain user name and passwords? what about their data? because if user X data is stored on computer A and if he is logged in to computer B then his data wont be available to him , right? So he must store his data to domain controller folder to his respective folder so that his data should be accessible any where in office on any system.

What about sharing printers in domain environment, for example one printer is connected via USB to computer B so how to make it a sharing printer so that computer A can also use it? I am very well aware of printer sharing in work group environment when a printer is connected to a PC via USB.

If possible attach some images OR send me some link where I can have the guide for all above asked questions with images because with images it is quite easier to understand, instead of reading.
waiting for your answers.

Kind Regards,
Wajeeh