At the house Im currently residing in, they have a Virgin Media ADSL connection, being fed into a Belkin F5D9630
When the router side of this POS gets stressed, it crashes.  Im wanting to turn off all the firewall and stuff and use it soley as a modem.

To provide the routing/firewall duties, Im wanting to use my DD-WRT equipped Linksys WRT54GS.  I cant work out how best to have this set up, or even get it working in a satesfactory manner.
 Any tips?

The Belkin does have an option for modem only, but then it removes the username/password boxes.

Belkin
Currently its set to Wireless Disabled, IP  Pool 192.168.2.3-192.168.2.100, Firewall OFF, NAT - ON. DHCP Server ON

Linksys
Set to IP 192.168.2.2, DHCP Forwarding off, DHCP Server Off,

The easiest (but not necessarily best) way would be to give the belkin a fixed ip (192.168.0.1) and set its DMZ to 192.168.0.2

Then set the Linksys WAN port to a fixed IP of 192.168.0.2.
Then set the Linksys up to do all the DHCP/router stuff.

At least thats what Id do, cheap and cheerful

I did try that, or something similar anyway, but it seems the belkins router cant be fully switched off.

Ok, Belkin is back as DHCP Server and the Linksys is the forwarder.  The routing and the wireless are taken care of by the DD-WRT Linksys.
Physical Lan port 1 from the Belkin is going to the WAN port of the Linksys, which is then set to DHCP.  The DNS and Gateways point back to 192.168.2.1 (Belkin)

FAIL>

Assigned WAN port to switch, Port 1 from belkin is feeding WAN still.  But the linksys thinks the WAN port is now part of its switch.

It wouldnt let me on the net trying Nimrods suggestion.  The only way I can get my Xbox out through this setup is setting it to be the DMZ on the belkin, making me believe you cant switch the router off fully.  Is there anything I can try with the NAT?

On the plus side to all this, the general web browsingness is a hell of a lot faster than relying on the Belkin.

When the belkin is feeding the linksys, it doesnt allocate the WAN port a proper IP, it says 0.0.0.0, and if I assign one it crys.  I believe this is a crucial part to getting DMZ working properly.

TBH Id just buy a new modem, far easier (though it does mean spending money).

Ive had experiences with belkin routers and Id do anything now rather than use one.

flip the belkin to "Bridge mode" and plug the linksys in for doing the wireless and routing.

The only options I get are
-PPPoE
-PPPoA
-Dynamic IP (1483 Bridge)
-Static IP (IPoA)
-Modem only (Disable Internet sharing)

Would the 1483 bridge mode work alongside PPPoE on the Linksys, as opposed to the stock PPPoA that the belkins connecting with?

Quote from: soopahfly-Modem only (Disable Internet sharing)

Bingo!  

Tried that, but wont allow me to enter a username or password.

QuoteSetting your Connection Type to Modem Only (Disable  
Internet Sharing)
In  this mode,  the Router simply acts as a bridge passing packets
across  the DSL port.  It requires additional software  to be  installed on
your computers  in order  to access  the  Internet.