As already mentioned before...
You can share the cable with ICS, just need a pair of network cards, one for your computer and one for hers.
And if you insist on dial-up, I hear juno is quite good for what you get, not that I've tried it myself.
And if you're lucky, you'll run into sales on occasion for a cheap router. Staples had a Linksys 4-port for $10CDN a while back, regularly goes for $140CDN. If only I got my friends to each get one for me on top of the one I got myself, as it was only limit one per person.