> Has anyone tried TSM for Exchange together with Exchange 2003? Does it
work?

Niklas,

We are working on Exchange 2003 support right now.
Look for Data Protection for Exchange to support
Exchange 2003 somewhere in the timeframe when it is
officially released from Microsoft or soon after.

As far as DP for Exchange 5.1.5 working with Exchange 2003...
Microsoft changed a registry entry that causes 5.1.5 to fail.
If you manage to modify the registry to fix that, there
will be problem if you have a Recovery Storage Group enabled.
The best thing will be to wait for the official support.

Thanks,

Del