The workgroup is just set as standard. You can change it in the file /etc/samba/smb.conf There is a line

workgroup = MSHOME

change MSHOME to what you want. You have to be super user to change the file, So the best thing is to use ALT+F2 and then enter "sudo gedit /etc/samba/smb.conf"

The issue that you can not see anything when you click the icon is a authentication problem. You have to create either users to authenticate on you ubuntu machine for the samba authentication, or you have to setup a security model that either joins the existing windows domain, or allows just sharing without authentication as it was used in windows 98.