Windows 2000 backup runs too slowly

We are trying to use Windows 2000 backup (Ntbackup.exe) to do an online backup of a remote Exchange 5.5 server, backing up to a DLT tape. When we run this backup on an NT server, it runs very quickly. When we try to do the same on a W2K server, it is extremely slow and says that it will take over 1 day to back up. We have tried backing up other files on remote servers also, to eliminate it being strictly an Exchange problem, and everything we try to backup remotely using Windows 2000 is s…l…o…w. We’d like to get off of the NT server, but cannot find what is causing this! Any ideas would be appreciated!