problem with dual network ports

Windows XP service pack 3
my PC has two network cards. One for general internet access (first port)
and another (second port) for data collection from another device. I have
to collect data on the second port, I can't do it on the first port. The
second port ip settings are just ip address and subnet mask, it has no
default gateway or dns settings. Problem is my PC sometimes 'chooses' the
second network port and I don't get any internet access. Is there a way to
configure the pc so that it only chooses the first network port for general
internet and network and ignores the other one? Thanks for any help.