For each user to have there own data drives, you will need to give each user a seperate account.
You can setup seperate ibays for common data - like the listing program or whatever and make a group for that and assign user to that group.
eg ibay = listings, group = list_group members of list_group=w, x,y,z
Then re-work the netlogon.bat to map those ibays.
You will end up with machine that are identical in terms of drive mapping for each user with the exception of the users home drive.
Beware of roaming profiles though - I both love them and hate them. I love them for what you are trying to achieve here. I hate them because more problems arise from damaged profiles than from anything else. Sometimes those problems exhibit themselves in ways which are very misleading and will send you down a very different path to where you should be going. Also, it helps if all workstations are identical. oftware & Hardware. Build one and "ghost" the rest.
You will find a thread in this forum with some fancy logon scripting software. I tried it and it works quite well.
HTH
P