Forgive me, but why are you thinking of a wireless connection if you just have the one machine?
You can use the broadband service on any phone extension in the house, simply by plugging in a microfilter to the socket, and then plugging your modem into the microfilter.
It's obviously for you to decide, but a wireless router and network card for your PC will set you back a reasonable sum, and with one computer you might not be gaining anything - the wireless connection will run slightly slower that a conventional modem system.
If you do go ahead you'll need to buy:-
1. A wireless modem/router combination, or (if you want to keep using your ADSL modem) a wireless router.
2. A wireless PCI card adapter for your desktop machine. Alternatively you can use a USB adapter if you're not keen on opening the computer's case.
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