I need advice with active directory and setting up profiles

I recently started a new job and notice user profiles in Active Directory WINDOWS SERVER 2003 are set up differently then we did them previuosly. It is probably the correct way, but I have a few questions. Users in this office have MY DOCUMENTS and their DESKTOPS stored on a common server. It seems to happen automatically when one is created. I discovered this when heard complaints that users could no longer save to thier desktops due to being out of space. When I looked closer I noticed the server that had all profiles was full. I used to manually point MY DOCUMENTS to a shared drive at my previous job, but this seems to be happening automatically with MY DOCUMENTS and DESKTOP. I have previously always stored the desktops on the C drive, but I can see how vaulable it is to have them all on a common server that gets backed up. I am just not sure how to set this up if I had to do it again. Is it possible something in the DFS. All suggestions are welcome