Two solutions for your problem which are typical of sharing internet between 2 computers:
1. You need a router; not a hub. Connect cable/DSL modem
to the Router using cat 5 cable (not cross-over cable which
is only useful for connecting only TWO PCs). Then connect each PC to the Router using cat 5 cables. The advantage is that you can turn off any PC any time.
2. If you don't have a Router, you need another Ethernet card and install it on one of the PCs; yes, this PC will have two ethernet cards. Connect your cable modem to one ethernet card on this PC and connect another PC with this PC using the OTHER ethernet card. (You may use cross-over in this case if you only have two PCs).If you have more than two PCs, then ignor the cross-over cable and use the Hub, which can connect more PCs. Enable internet sharing if you use Win98. WinXP will share internet automatically.
Good luck.