Backup tapes work a little bit differently than your average read-write media . They typically contain proprietary information regarding their format and the data. You usually need to use a program that can understand this format to recover the data -- rather than just "read" from the tape as you might a CDRom or Harddrive with Windows Explorer.
To recover the files contained within your backup set from the tape, you will need to use NTBackup (or Veritas BackupExec, which can read NTBackup files). You will not directly be able to restore from tape to a BKF format that you may be familiar with NTBackup using for backup to disk scenarios.
The data that is written to tape actually is stored in Microsoft Tape Format (MTF), so any software that can read MTF can recover your data.
There are some good discussions on backup already on Server Fault. I'd have a look at them:
I notice that you're already ruling out tape. I'd do a cost-benefit analysis of the alternatives pitted against tape before dismissing tape out of hand. It sounds to me like you've either got a bum SCSI controller, cable, or bum tape drive and it's unfortunate that it has soured you on tape because tape can be very reliable and robust.
I did some calculations a few months ago (posted on Server Fault in one of the questions above, but not updated) and found that tape wasn't necessarily the most expensive route. Call me a traditionalist, but tape has worked very well for me and my Customers, and has proven to be reliable and suitable for disaster recovery. I tend to think that a lot of the "horror stories" associated with tape being unreliable often stem from backup strategies that don't involve testing of the backups after-the-fact. As is often said, backup isn't about backup-- it's about being able to restore.
Having a maintenance agreement for your hardware is, obviously, a component of any robust solution as well. You state that you need a backup you can restore to other hardware, but I'd caution you that your SBS server's "System State" backups aren't restorable by any Microsoft-supported means to alternative hardware. Hopefully your other server is a domain controller, since you'll be losing Active Directory (and, thus, making your Exchange data fairly difficult to get at) if you lose that SBS Server computer.
Having a maintenance agreement on the tape drive and / or server would get you out of the mess that you're in, in this case. It's particularly critical since you've currently got a backup, assuming you don't have another domain controller, for which you really need the identical server hardware available for restore.
You shouldn't center your whole backup regime around writing backups to an on-site storage device. Backup is off-site and offline. Anything less isn't backup.
I'd question if you can restore fast enough to get back up and running in a timely fashion if your main backup is an off-site device and accessible only through your Internet connection. If your renmote backup provider has a provision to ship you a physical storage device I could see that working. If you have to download your entire backup corpus over a consumer Internet connection, though, I'd think that you'd be talking about at least a couple of days to get everything back up and running. Ouch!
Best Answer
Rebooting Windows is the answer.