VPN/Firewall

Hi

I have a Netgear DG602 Router/Modem and a Netgear FVS318 VPN/Firewall.

Firstly I changed the DG602 into Modem mode and plugged it into the FVS318
WAN port. Then Netgear told me that these 2 devices are not comptible but
can still be used together by putting the DG602 back in router mode and
putting it behind the FVS318 (I assume this means in one of the standard
switch ports and not the WAN port).

So I have my IP conifguration as follows:

DM602 - 192.168.0.1
FVS318 - 192.168.0.2
Workstaions - 192.168.12.x with default gateway as 192.168.0.2 and DNS as
192.168.0.2 assigned by DHCP Server running on the FVS318.

The FVS318 (192.168.0.2) is in the DMZ of the DM602.

So my question is, why doesn't it work? Everything is pingable. However,
when i do "ping google.com" it replies as 192.168.0.2 and not as google's
IP. Infact every website is coming back as 192.168.0.2. How do I tell the
FVS318 to pass traffic across to 192.168.0.1 (i.e the DM602)??

Hope someone can help... TIA

Ol