Your ISP would actually assign you a (say) 4 address IP subnet, of which of course one address would go for the network address, one for broadcast and you would then have two addresses left. One address of these would be used for your Windows box and one for the Linux box.
That was funny....
You would have to enable IP forwarding on your Windows box for this to work.
U dont have to enable ip forwarding on ur windows box, if ur having ur linux box with a static ip. Setup ur services on ur linux box and have 2 nic's , one for the wan and one for ur internel lan, and don't ever enable ip forwarding on ur cards, unless u want outside people to access ur lan,and since it is with a static ip, firewall it properly..
regards, Prem.