3 networked pcs and one internet weird things

[krisuk2001]

ive tried posting this in the networking forum with out much response

i have 3 computers linked up with earthnet, net work cards
i have 2 earthnet cards in my computer one for my cable modem and one for the other 2 computers in my house iv changed the
ip for the lan network card to 198.138.98.1 for computer one...
computer 2`s ip is 198.138.98.2 computer 3`s ip is 198.138.98.3
iv added IPX/SPX-compatible protocol in my NETWORK NEIGHBOURHOOD and a NetBEUI
that way all three pc`s work together
when i start a server on computer 1 and some one wants to join
by the internet tcp/ip at the same time he gets my network address 198.138.98.1
he should get my ip for my cable modem its makeing the computer that is joining from the net crash please help i know its a hard one..........................if you can help you rock.......