Umm, i think you shoud scrap ics, and just run a simple proxy.
I use proxy plus to share my hathway conn between the desktop and the laptop.
Its free, light and fast.
http://www.proxyplus.cz/
After u install it on ur pc (which is directly connected to the net), just configure the ports, then go to the client, and add the proxy settings in IE and other browsers (if u use others)
thats it.
And put proxy plus in ur start up
Happy sharing