multiple network adapters

i already have my network working between two of my
computers that are using a cable modem, however to run
certain games i need a second network adapter. my first
computer already had two and works fine, but my second
doesn't seem to want to take on another adapater. Usually
it tells me that the driver i try to install is a plug and
play driver and won't let me install it. id appreciate
some help with this problem

scott