Ok, after much hard work and a LOT of messing around I finally nearly have this working.

Using Kubuntu, I've figured out that if I completely disable my wireless and manually set up wired connection, it will easily ping the 'dozeXP laptop and they will chatter as long as the Gateway on the Kubuntu box is set to 192.168.0.1.

However while it is like this, with the wireless enabled too, the wireless will NOT connect to the internet. But, when I change the gateway to 192.168.0.2 (on the wired connection), I can connect to the internet, but no longer ping the laptop box or communicate with it!! So I can have both of these interfaces active at the same time, I'm just misconfiguring something.


Laptop <--- Kubby Box <---- Wireless Internet Magic (Router)

Other things:

Wireless settings (eth1)

DHCP (No encryption of any type)
IP: 192.168.0.2
GW: 192.168.0.1 (the ip address of the router, of course)

Current wired settings (eth0)

IP (static) 192.168.0.10
Netmask: 255.255.255.0
GW: 192.168.0.2 (so I can post this...)

'Doze box

IP (I assigned, manual settings): 192.168.0.4
Netmask: 255.255.255.0
Default GW: 192.168.0.10
Preferred DNS: 192.168.0.1

Instead of replicating the IP address of the router on your computer, change the gateway settings of the windows host.

I have done something similar:
instead of
Laptop <--- Kubby Box <---- Wireless Internet Magic (Router)

I did
Desktop <--- Laptop <--- (Wireless) Router
to give the desktop access to the internet when it didn't have a wireless card.

I used a different subnet on the wired side then the wireless side.
wireless 192.168.1.0/25
wiredlan 192.168.1.128/25

These have a netmask of 255.255.255.128

Then I enabled IP forwarding on the laptop, and modprobed the ip_conntrack module. I used the LAN facing NIC ip address of the laptop as the gateway address for the desktop computer. That way, an internet address will be routed to the laptops IP address on its way to the internet.

I also had two net routes in the laptop
route add net 192.168.1.0 netmask 255.255.255.128 dev wlan0
route add net 192.168.1.128 netmask 255.255.255.128 dev eth0
route add default gw 192.168.1.1 dev wlan0

If you have two interfaces on the same subnet, you need a host route or have to use ip_tables rules. Plus, one of your interfaces has the same IP address as your default gateway (the router) which could cause problems.

Please note that my router is a NAT router so I didn't need to configure masquerading.

Wow, after plenty of studying your setup, I realized that I needed to change the wired ethernet's address to something other than what the router originally assigned. Instead of 192.168.0.10 I assigned 192.168.1.10. I kept 255.255.255.0 (I apparently also have a NAT router, so no masquerading was needed, unless firestarter is doing it for me.) I definitely am using a crossover cable with this configuration.

So Final configuration settings:

Wireless eth1

IP: 192.168.0.2 dhcp
NM: 255.255.255.0

Wired eth0

IP (static): 192.168.1.10
NM: 255.255.255.0
Default gw: 192.168.0.2
Broadcast: 192.168.1.255


Winbox
IP (static): 192.168.1.4
Subnet: 255.255.255.0
Default gw: 192.168.1.10
Preferred DNS: 192.168.0.1

Can't thank you enough for opening my eyes to the problem. I seriously have been working off and on with this crap for about two years. Brilliant.