I have a network of 3 OS X & 3 XP machines. I use Samba for file sharing and have set up groups in OS X and workgroups in Samba. I am trying to share an MYOB file across multiple Macs Using XP as the file server. The permissions that show up on OSX show up as group "wheel" and read only. I need the group to show up as the workgroup with rwx permissions.
Try setting up a new workgroup... go the properties to your C drive then click on the sharing tab then click on the new button add the mac users to the group and set the permissions to what you would like them to be and that should do it if it doesnt let me know.