networking vista with xp

I have a LAPTOP running vista and has wireless and wire Ethernet interfaces.
Using the wireless interface (home network) my laptop can see my wired XP machines. Using the Ethernet interface, wired (office network) the LAPTOP will not see the XP machines (in this case I have the wireless switched off). I have the correct workgroup, loaded LLTD Responder in XP machines but with no result. The XP machines will show the VISTA machine but can not ping it. The vista will not see the XP machines but can ping them.
Any ideas..?