Sorry if this is a little basic,
Is TCP/IP installed properly.
Is each card configured for DHCP.
If you use manual settings can you ping the device with the DHCP server
Is DHCP turned on server side?
Does DHCP have all required ip ranges, static exclusions, etc configured
Have you rebooted the device with DHCP in case server has hung
Is DHCP configured correctly to send ip config info to your card
What does ipconfig /all from cmd reveal assuming xp
what does ipconfig /release followed by ipconfig /new reveal
Different known working cable?
Its been a long time since I did the training courses but I vaguely rememeber DHCP uses network broadcasts during the renew process. Does your firewall setup block broadcast traffic?
If you only have a few PCs its probably better to use a manual IP schema anyway as devices like routers, print server will need to be non-DHCP anyway
Hope something is list above points you in right direction.