Connecting to two ISPs (Split configuration on one Router)

Hi,

I want to set up a split configuration to send data to two different ISP's from one Cisco router. I have four Ethernet ports, one each to ISP1 and ISP2, the other interfaces are for 2 different network subnets from ISP1 and ISP2. Users that from ISP1 subnet 192.68.100.0 must use ISP1 and users from ISP2 subnet 192.168.200.0 have to use ISP2.

There is one problem in this config that I cannot split the default route

ip route 0.0.0.0 0.0.0.0 x.x.x.x

Is there a way to make a route based on the source address so I can split the traffic to the correct interface to the ISPs

Thanks in advance,

Chidi