allow other pc to access the net ?

Hello ,
I have two computers , A and B, they are connected to each other using a hub ,
only pc A is connected to the internet through dsl connection ,
now I want the other pc (B) to have access to the net if :-
1- pc A running Linux and pc B running windows xp.
2- both pc's are running windows .
3- both pc's are running Linux.
thanks.

Well I can help you with the second point.

On computer A, right-click the Internet connection and make sure that Internet Connection Sharing is enabled. Make sure that this computer has a static IP address such as 192.168.0.1. On the second computer, set the default gateway to the IP address of the first computer (such as 192.168.0.1). You may also need to configure the DNS servers to point to the IP addresses of the DNS servers provided to you by your ISP.

from your reply on the second point , i can deduce a soultion for the first and the third , but i need somebody to confirm me , please if someone knows , tell me .
for case 1 :
in the A box , windows , i do just as you told me ,
in box B , Linux , i do the following :
#ifconfig eth0 inet 198.168.0.2 netmask 255.255.255.0
#route add default gw 198.168.0.1

for case 3 :
in box A :
#ifconfig eth0 inet 198.168.0.1 netmask 255.255.255.0
in box B :
#ifconfig eth0 inet 198.168.0.2 netmask 255.255.255.0
#route add default gw 198.168.0.1
==========================
is this true ??
thank you , edwinbrains.