is samba working / active and using the following:
http://www.cyberciti.biz/tips/howto-...mb-shares.html
Can your ubuntu server see its own shares via samba.
From the windows box can you ping the server?
What happens if you go to \\servername\ does it prompt you for a login or does it auto show the available shares?
Any firewalls active and blocking the samba ports?