Ways of updating Backup Exec:

• You can navigate the Veritas/Symantec support site for the Support: Backup Exec for Windows Servers page entitled Software Updates & Downloads.
• You can use the Veritas Update feature of Backup Exec.
• Update: The following method was not usable as of 2006-11-07, when I discovered that many (if not all) of the needed subdirectories are now restricted. -sigh-
  My preferred method: You can FTP to ftp.support.veritas.com, navigate to /pub/support/products/Backup_Exec_for_WindowsNT/ and sort the directory by date in descending order. Then you can grab the latest driver or software update which is listed nearest to the top of the list. You can even go straight to the relative support article by typing the number from the file into the Veritas/Symantec support site search field.