Data Protector Express - definition of Client

[Thomas Hartenstein]

I get the information that it´s possible to unlock the "Data Protector Express Single Server Edt." to the Full-Version.
With this full Version it´s possible to Backup an unlimited account of clients.
The definition Client seem´s to belong to the operating system.

For backing up servers its necessary to buy "Network Server Backup Agents", one for each server.

But my question:
I like to backup only some network directories from a additional Windows 2003 Server. In this simple case I also have to buy a Server Backup Agent ?

What´s about Linux-machines. Makes the Data Protector there a difference between Clients and Servers ?

Greetings
Tom