Hello Angel,
First I would like you to confirm which product you are trying to install. Please check if it is Backup Exec 2010 or Backup Exec for System Recovery (BESR) 2010.
From the above description it seems that you are trying to install Backuy Exec 2010 as you mentioned that you have around 10 server with windows 2003 server in our network , with exchange 2003 , Domain controllers etc etc etc...
So here is the technote which you can refer to download and install
BACKUP EXEC 2010
http://support.veritas.com/docs/347372
As you have already download the software you may have to follow from step
[ II ] Install Backup Exec 2010 for installation.
Hope this piece of information helps you...!!
If this answers your queries then you can mark this response as Solution