What should happen is the ICS wizard takes you through the process and you end up with (amongst other things) two TCP/IP entries in the network properties, one marked 'home' bound to the network adaptor and one marked 'shared' bound to the h/w used to connect to the net. ICS handles the connection between the two.
Now on the PC just to the left, what actually happens is that the two TCP/IP entries are set up but the latter one, bound in this case to a dial-up adapter, does not have the vitual 'shared' annotation.
And the ICS doesn't work. Even on the host PC, you can't successfully talk to the outside net. Try, and the modem will dial out and connect, but you can't actually send or recieve any data - pings don't work, for example.
Looking at the MS website, I've come across this Powerpoint presentation which takes people through it visually. Jump to slide 16ish and you'll see the dialogues that are meant to appear if you choose a dial-up internet connection and a 'high-speed' one in the wizard.
Interestingly, although in the numerous times I've installed, uninstalled and reinstalled ICS, the dial-up dialogue - where you pick which dial-up connection to use - has never appeared, even though it was told to use the dial-up to access the net.
I'm seriously wondering if this is a sign of what's wrong. I've uninstalled and reinstalled Dial-Up Networking, but it still won't give me this dialogue.
It has just occurred to me how silly this is, given that a new machine will be here soon and will be pressed into service as the net connection, but I want to get this working... Grrrrrr.