problem with ICS with win 2000 server

Hello,
I need some help on fixing the internet connection sharing on wondows 2000 server.

i have one server and two clients , i got an internet connection from btworldonline ADSL. i have an DHCP , DNS on the server.

now the problem is that the internet  won't work on the clients computer (win 2000 pro) when i ping the client computer form  the server i get  a responce and when i ping from the client computer to the server i get an responce too .
the client computer picks up the ip i have  assigned to the dhcp so thats working fine , i can see exaclly what ip it has picked and is working fine there isn't n problem with the networking we can share files , printer and so on ...

i've set up the ICS on the  btworldonline dial up and it said it will change the ip to 192.168.0.1 . is done that and everything has changed .

but stillthe ICS won't work.
can anyone help me
i'd be really greatfull
Thank you
Marty