I have just ordered sky broadband. They are sending me a wireless router but how do I make my desktop computer wi fi if it doesn't have it built in? Do I need to buy something. Please help, I know very little about PC's
... but just because you have a wireless router you don't HAVE to connect wirelessly. You can connect an ethernet cable from your machines network port to a port on the router.
And to further rojash's answer...
If your router is going to be very near your computer anyway, just use a cable as usual. You'll get better reliability.
your wirelesss router they send you should include a usb wireless adapter with a cd with the driver on it all you then have to do is install the driver plug in the usb device and get going :-)