Neil
The supported formats to restore data for Backup Exec are (administrator's guide):
Backup Exec for Windows NT 7.3 and later (MTF)
■ Backup Exec for NetWare Servers 7.x, 8.x, and 9.x (MTF)
■ Software-compressed media created with previous versions of Backup Exec, such as
Backup Exec for Windows NT (5.x, 6.x and 7.x)
■ Seagate Backup Director (SIDF)
■ Seagate Storage Exec (SIDF)
■ BrightStor� ARCserve� Backup 9, 10, 11, and 11.5 for Windows
■ Novell SBackup (SIDF)
■ Palindrome Backup Director for Windows NT and NetWare (SIDF)
■ Palindrome Storage Manager for Windows NT and NetWare (SIDF)
Note Software-compressed data backed up with products other than Backup Exec for Windows Servers cannot be restored.
I'm afraid there's no way without reinstalling...