how do I setup a multi default gateway accessing at a time in windows 2003?

I recently added two different networks in 2 Nic’s inwhich one NIC onbaord itself and other one is external and also config following routing command.
C:\>route add -P 0.0.0.0 mask 0.0.0.0 97.x.x.x metric 1
C:\>route add -P 0.0.0.0 mask 0.0.0.0 10.x.x.x metric 1
Both are working initially thereafter 97.x.x.x is not working and no one can access this gateway, then I remove the 10.x.x.x gateway from LAN setting those route is working but this one cannot be accessed at this movementeven though I added the metric value in LAN settings. At a time only one gateway is accessing. Thanks in advance.