<< Ok, so you have one cable modem, with a laptop connected via USB, and a PC connected via ethernet? I wouldn't do it through the cable modem. Too many security issues IMHO, especially with both WAN and LAN traffic using the same NICs with the same external IPs. Isn't there some way to get an ethernet connection off the laptop too? Maybe a USB NIC? Then put another NIC in the PC and connect the two NICs with a crossover cable.
Edit: IMHO if you want to do this right, get a NIC for the laptop, and a cheap ethernet router. Plug everything into the router. Then you can have secure LAN file transfer and still be sharing the internet access.
[/b]Edit #2:[/b] Isn't Win XP's firewall on by default? >>
The laptop has an ethernet port. Is there like a network splitter so on the desktop one can go to the modem and one to the laptop?
And yes, the firewall was on by default 🙂 The included help is actually pretty good.