Lots of them..LOL..At present I use NT Backup every day to back up 4 servers. Be aware that NTBackup does NOT backup open files!!! Having to restore files can be a real pain in the butt. The tape, with the header you THINK is there, might have a totally different name all togather and NTBackup will ask you to first load an older tape with a different name. Like I said, a real pain. And not very fast if you are writing to tape.
If you can, I'd think about using something like ArcServe from CA. Pricey, but better than NTBackup. I'll be installing ArcServe, hopefully, within a month or less, along with a new tape library unit.