I guess a lot of things can go wrong. The first few things that come to my mind is:
Did you buy a card that comes with good working xp drivers? If it looks like it is properly installed you can verify that by using it for the internet connection instead of nic #1. If it work we know tha hard- and software both machines work properly.
Have you changed the way the machines are connected to each other? Ie is there a hub or switch between them, was it the same way before you bought nic #2 and do you use a proper working cable?
__________________
unicorn
|