try cifs, some of my win2k3 servers at work only work with cifs (Large Filesystem support)
//servername/sharepoint /mnt/mylocaldir cifs, credentials=/home/foo/.servernamecredentials
make the credentials file like this :
(in a console)
navigate to /home/foo (where foo is your username)
# echo username=foo > .servernamecredentials
# echo password=secret >> .servernamecredentials
# chmod 655 .servernamecredentials
bear in mind that on my network (at work) there are 10 workgroups and 2 domains, so the network is iffy to say the least.
if you are on a Domain you might find browsing the network easier by joining the domain, if i remember correctly that can be done using :
#net ads join -w workgroupname
(for active directory)
you will be asked for the password of the user logged in and then you should be joined and appear as a machine in the domain.
hope this is of help