LAN giving problems?

Hi all,

I recently installed a plug and play Ethernet adapter into my pc which is Win7. I am trying to LAN with a windows XP pc (which previously worked with my onboard adapter).

When I view the status of the Local area connection, it shows that there are packets being sent and received to and from both pcs. But I CANNOT see the win XP pc in my network as I am not on the existing network with it?

what you mean you can not see?
can you ping the other pc?
is firewall configured and network detection and file sharing on?
if you type "\\[computername]" (or ip) does it work?
does they have good ip configuration?