I agree. RARP protocol on ethernet interfaces is flaky on Ciscos. Particularly when it's the default route. I don't like it, so I don't use it.
Here's a real simple config:
version 12.0
service timestamps debug uptime
service timestamps log uptime
service password-encryption
!
hostname Router
!
enable secret 5 <blah>
enable password 7 <blah>
!
ip subnet-zero
no ip source-route
no ip finger
ip tcp synwait-time 10
ip name-server xxx.xxx.xxx.xxx
clock timezone CST -6
clock summer-time CDT recurring
!
!
!
interface Ethernet0
description Internal NAT IP Interface
ip address 192.168.0.1 255.255.255.0
no ip directed-broadcast
ip nat inside
!
interface Ethernet1
description Outside NAT IP Interface
ip address 66.x.x.x 255.255.255.248
no ip directed-broadcast
ip nat outside
!
ip nat inside source list 1 interface Ethernet1 overload
ip classless
ip route 0.0.0.0 0.0.0.0 <next hop (66.something)>
!
access-list 1 permit 192.168.0.0 0.0.0.255
!
line con 0
transport input none
line vty 0 4
password 7 <blah>
login
write erase and start over.
