If you're worried about your NIC, then before the Internet you should concern yourself with simply pinging the other PC.
You say you have 2 PCs, can both "see" each other ? Do you have shared disks on both that can be seen by the other ?
If your PCs can participate in normal LAN activity, then your card is not at fault. If the PCs cannot share information, then you probably still have a setup issue. You might want to try removing all network components entirely from the PC that doesn't network, and rebooting to reinstall them correctly.
I have been using network cards for the past 10 years, and I have yet to find one that doesn't work. Of course, I'm not saying it can't happen, but I do believe that it is rather rare.
Pascal.