backup system for servers

[xserver80 <xserver80@gmail.com>]

Hi All
I need to schedule the data backup for 3 servers (2 Debian and 1
Windows) into a dedicated server.
The problem is that I can't install any software in none of the data
source servers (2 Debian and 1 Windows).
The object of my backup are the data exported with samba (2 Debian
Server) and ftp server (Win Server).
That system should mounted the shares (samba and ftp) for download and
check data in other system server.
In the future my boss will ask me for the copy of data backup
exsisting in the dedicated server backup in the  LTO type carthage (or
similar).
Now I am looking for a software or hardware system to do that.
If I don't find any dedicated hardware system I will prepare a
dedicate server with big area storage inside.
I don't think that a script is a good idea, because I need to keep
data saved for long tine and I need to check data during or after each
backup cicle. (check data transfer and dada consistance).
Can you help me to find a solutions?
I will evaluate all solutions thet you post me. Whatever, software and
hardware, commercial or free.
I must show to my boss the best solution. :-)

I thank everybody in advance.
Alex