Cisco 1602 route problem

Not sure what I missed here but,

I have an ISDN router with DNS at 192.168.2.1
A Cisco 1602 at 192.168.2.2 (A network)
A Livingston at 192.168.1.1 (B network)
Cisco and Livinston joined by a DS0 on Serial0
Cisco joined to ISDN router by Ethernet0

I can access everything in the private networks (A & B) but nothing in the real world.  If I set the computers on the A network to use the ISDN as the gateway, the outside world resolves... any idea what I missed/blew?

Thanks in advance
--Lee

P.S. one other interesting note... the ISDN router appears to only be capable of dealing with class D addresses 1-15.


Cisco config
------------------
'version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname CISCO
!
enable password xxxx
!
ip subnet-zero
ip name-server 192.168.2.1
!
!
interface Ethernet0
 description connected to Internet
 ip address 192.168.2.2 255.255.255.0
 no ip directed-broadcast
 ip nat outside
 no keepalive
!
interface Serial0
 description connected to Cisco1602
 ip unnumbered Ethernet0
 no ip directed-broadcast
 ip nat inside
 encapsulation ppp
 no ip mroute-cache
 service-module 56k clock source internal
 service-module 56k network-type dds
!
ip nat pool Internet 192.168.2.1 192.168.2.1 netmask 255.255.0.0
ip nat inside source list 1 pool Internet overload
no ip classless
ip route 0.0.0.0 0.0.0.0 Ethernet0
ip route 192.168.1.0 255.255.255.0 Serial0
!
access-list 1 permit 192.168.0.0 0.0.255.255
snmp-server community public RO
!
line con 0
 exec-timeout 0 0
 password xxxx
 login
 transport input none
line vty 0 4
 password xxxx
 login
!
end