OS installation
Ubuntu
Ubuntu installation disks (12 and 14) are available in admin shelf and can be used for OS installation (or re-installation).
The root password to be used are available in "local passwords" page in lastpass account.
Make sure to assign the correct (previous) internal IP address to the system after installation.
Installation steps are available in:
http://howtoubuntu.org/how-to-install-ubuntu-14-04-trusty-tahr
Windows
Windows (7, server 2005, server 2008) installation disks are available in admin shelf and can be used according to requirement.
The administrator account should be made with the windows admin password provided in lastpass (local passwords).
Make sure to assign the correct (previous) internal IP address to the system after installation.
Note: In case of any system not having a DVD drive, one is available in admin shelf and can be connected to any systems.