Hi, I know I am being a dummy and I am sure someone will point out the error of my ways ver quickly.
We are swapping internet provider from PSInet to BT, new IP addresses and all that. The current setup is 2 nic cards eth0 and eth1, eth0 is connected to the cisco router and eth0 connected to a switch which provides internet connection only to approx 15 pcs. I have amended the hosts, resolv.config and the interfaces files with the new ip addresses. From my internet pc I can Putty into the server, via eth1 but I can not connect to the internet. From home I can connect to the server via Putty using the ip address of eth0 card. Why can I not connect to the internet from the internet PCs? Ping does not work on the web server so I can not check while at the server if I can connect to the internet.

When I go back to the original config it works fine.
Any ideas

The default gateway on the computer with 2 internet devices should use the ip address of the cisco router using eth0. You shouldn't have needed to change the computers values with the new IP addresses but change the internet address on the WAN side of the cisco router.

The only nic card I altered was the eth0 which has the IP address of the cisco router as the default gateway, the other nic card has the virtual network ip addresses does the 15 internet pcs.
Do I need to tell one nic card the address of the other so they can communicate?

Problem sorted, I had not configured the IPtables correctly. Doh Doh Doh!