Currently I have two ways of Connecting to internet ie., I am using two broadband connections they are Hathaway broadband and airtel broadband through two ethernet cards one is built into motherboard and another external,they all connect to my access switch S5700-28C-EI.

I am able to browse internet using any of the above connections. The issue is Hathaway broadband is frequently disconnecting and airtel broadband is providing services without interruption.
Hathaway is providing data download at very low cost and airtel is providing data download at very high cost.

I am using openSUSE12.3 as my operating system. When I issued the command ifconfig it is showing message as Hathaway is assigned to eth0 and airtel is assigned to eth1.

I want to achieve the following goals
1)when I download any file the system must use Hathaway ie., eth0
2)when the Hathaway broadband disconnects the system must immediately switch to airtel broadband ie., eth1

This question has been asked before, in a very similar form.
Please see viewtopic.php?f=18&t=119226 and http://forum.kde.org/viewtopic.php?f=18&t=118083 for more information on solutions.