We're using Veritas Netbackup Pro on the desktop to a local server and then backing up the server with a DLT drive. The beauty of NB Pro is it handles incrementals very well. It only backs up the pieces of a file that actually change, not the entire file.

This is very useful if, like us, your users have huge pst files that change every day.

Cost was about $200/client + $6k for the server & tape drive. Not the cheapest solution in the world, but, then again, how much is your data worth to you?