Adding wireless laptop to eMac cable modem

You can do this with a wireless router - any model sold by your local computer shop will do, and should cost you around $30-60. At home:
- connect the cable modem to the router's WAN or "internet" port
- connect the eMac to one of the router's LAN ports
- your new laptop will of course connect wirelessly

All this can also be done exactly as I described with an Apple Airport Extreme Base Station (costs $199). For that premium price you get a device that is arguably easier to set up for Mac users, and you get a built in USB port that can be used to share a connected printer between both the eMac and the laptop.

If you install a airport card into you emac you can go under sharing in your system pref's and turn on Internet sharing via airport.

Yes he could - but for the original 700MHz eMac that Richard owns, the cost of the required original Airport card is now over $150.

For arguments - pro and con - to using a "software base station" vs a wireless router, see the user contributed tips article Software base station or wireless router