1. Buy a wireless broadband router - one that has its own ADSL modem built in. There are literally dozens to choose from.
2. Then install an ordinary LAN card in the computer that's near to the router.
3. Buy a wireless network adapter for the second computer. This can either be internal (PCI slot) or external (USB), and won't be expensive.
4. Set up the router (takes about 15 minutes) by connecting a lead from it to the ADSL microfilter, and a LAN lead from the router to the first computer. You will now have broadband internet access on his machine via the router.
5. Install the wireless network adapter in the second machine. If you’ve opted for an internal PCI type you need to open up the case, insert the card and let Windows XP detect the card. Cancel the Windows default driver installation and then use the driver disk that comes in the pack. If you’ve opted for a USB type adapter, install the software BEFORE connecting the device.
6. Now reboot everything, including the router, and watch the computers pick up the internet connection. On the wireless machine it will probably be necessary to click on the adapter icon in the system tray (bottom right) and tell it to detect wireless networks (although it may do this on its own). Then tell it to use the connection it finds.
That's it - you should have two machines sharing the connection via the router. You don’t need to leave the router on all the time, because it will automatically login to the broadband gateway each time it's turned on - all you do is watch the lights.