Tape Backup and Restore Strategy

This question is to enquire about packages available for Tape Backup Software. We are using the standard NT backup from a server to the Dell PowerVault 120T DLT for the backup of data on our LAN. We are in a Windows NT and 2000 server environment with about 40 servers. I need to implement a backup and restore strategy for certain shared files and our test databases. I need recommendations for software to use to backup open files and/or non-open files. Unfortunately I have no budget to work with. I hope you can be of help or provide some suggestions on software available and a backup strategy.

Thank you in advance for your help.