please please help

i bought a network card (realtek 8139) about 5 months ago and i still havent
got it going. could someone please tell me wot to do. i can share files from
computer to computer but cannot get any games to work. why is this i read in
a few forums that it may be interfering with my sound card, but i am no
computer expert, how does one know this or fix this. i have installed and
uninstalled protocols and etc. please help anything would be great