Make added routes permanent

I have added some routes to make my networked linux box run a special configuration.  I entered the routes in /etc/rc.local so they are added at startup.

I seem to be having issues where the routes are lost after some time.

What files do I need to add these routes to so they will be permanent?

Running Centos 5.5

Here is what I added:

ip route add 192.168.1.0/24 via 192.168.1.1 table 192
ip route add default via 192.168.1.1 table 192
ip rule add from 192.168.1.0/24 table 192
ip route add 10.0.0.0/24 via 10.0.0.1 table 10
ip route add default via 10.0.0.1 table 10
ip rule add from 10.0.0.0/24 table 10

I would also like to keep the default routes...
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
10.0.0.0        *               255.255.255.0   U     0      0        0 eth1
192.168.1.0     *               255.255.255.0   U     0      0        0 eth0
169.254.0.0     *               255.255.0.0     U     0      0        0 eth1
default         192.168.1.1     0.0.0.0         UG    0      0        0 eth0