Build a workstation with a good CPU, RAM and oodles of hard drive space.
Then you either use any of the opensource products to synchronize data from your main server to this workstation, one-way only, so that deleted files on the main server does not get deleted on this workstation.
This makes recovering from accidental file deletions much easier.
And, should the main server bork for whatever reason, you'll have a good backup which'll be out by a few hours, and which the users can use to proceed whilst you're rebuilding the main server. Very little downtime.
But my recommendation is to still do tape backups just in case. Tape backups together with this type of synchromized workstation/server will ensure speedy recovery from disaster.
The idea then, is to put your tapes offsite, and should data corruption occur, then you know you can refer to the tapes.
Luckily data corruption is very scarce, but it can (and might) happen.
I do hope you've set up a backup domain controller just in case...
