I do tar backups in a similar fashion and haven't hit problems, buuuuut...

My tar backups go into a temporary loctation on the local drive, and
then I copy them to the Windows server using smbclient, then delete
the tar files on the local drive. It's all scripted.

-- 
Andrew S. Zbikowski | http://andy.zibnet.us
 A password is like your underwear; Change it
 frequently, don't share it with others, and
     don't ask to borrow someone else's.