Your G4 will gladly handle the data for the increased speeds. Plus, you won't have to buy a card with an ethernet connector like PC users do. The ethernet jack is a little bit bigger than a standard phone jack which is the modem jack on the back of your G4. You'll need to get an ethernet cable to hook up your new DSL or cable modem to your G4, but chances are that this will be provided by the your high-speed Internet Service Provider (ISP), the company you're going with to get the high speed connections. If, down the line you add another Mac in your house or apartment and you want them both to be able to get high speed internet access, you can get a router (around $20-$30). The High speed line will come from the phone jack (DSL) or the coaxial cable (cable from outside), which will be hooked up to the modem. The modem will be hooked to the router, and the router will have an ethernet cable going to each Mac. Feel free to write back if you need help on setting that up. Eric