DHCP Problems

I have a netgear dg834g router and two wireless cards with all systems running xp the wireless computers connect fine to the router with the router assigning the ip addresses and accessing the internet as it should however the pc connected via the cable sometimes accepts an ip address from the dhcp i have managed to get it working several times but it stops working i have tried all manor of things to get it working with some success but when it stops working i try the things i did to get it working and they dont work its always by accident i get it working again. Help on this matter would be muchly appreciated as i am tearing my hair out over the situation.

 

Have a look here.

http://kbserver.netgear.com/products/DG834G.asp