Not totally sure about this but worth a try.
I'm pretty sure the mount command "mount -t smbfs -o username=xxxx,password=xxxx //servername/share /mountpoint" should have the servername rather than ip address - at least that's how I always connect.
As regards you Windows workstations check on the permissions tab who you are giving access to for the shares you are trying to browse. It can either be individual users or something like domain members.
In my own setup my linux Samba server is the PDC but I share the Windows printer attached to my Win2k machine which logs on to my domain. To use that resource from linux the relevant bit from the linux printing manager was "smb://user
assword@server/printer_share_name"
Sorry I can't be more specific but I'm at work and hence linuxless - I'll check it out tonight.
As regards the mount -t ntfs - that's for a ntfs drive on the machine you're running eg a windows partition.