Webmin will allow you to setup and change access rights for samba shares and nfs exports along with a whole range of other things very useful for configuring your pc/server.
Usermin allows users on your Linux system to change details about themselves, such as their own name if they get married, mail forwarding, their spam filtering, view processes running as their usernname (ie their cron jobs), mount filesystems listed, get a terminal in their web browser via tenet or ssh to the linux box, view their disk quotas etc. Neither webmin or usermin can set up 'drives' for these network shares.
If both usermin and webmin are installed on your system try them out by pointing your favourite browser at
https://localhost:10000/ for webmin and
https://localhost:20000/ for usermin. You will need to log in as root at the webmin login page. You may get auto-logged in to usermin if you're running your browser as a normal user. To see root's usermin's options you will need to start your web browser as root, or login via kde/gnome as root and go from there.
