Hi,
If you have license for "Backup Execfor Windows Servers" then you can backup a remote SBS server and would require an extra remote agent to be installed on the SBS server.
Also refer: http://support.veritas.com/docs/253755
We would also like to clarify that the SBS edition of Backup Exec is meant to be installed only on SBS edition of Windows OS.
For any purchase, upgrade or licensing issues, you can contact our Sales:
http://www.veritas.com/contactus/ContactUsHome.jhtml
NOTE : If we do not receive your reply within two business days, this post would be marked "assumed answered" and would be moved to "answered questions" pool.