In order to change your broadband connection to a wireless setup, you'll need a wireless router to plug into your phone socket, and a USB or PCI wireless adapter attached to your computer. If you don't want to open up your computer and install a card, then go for the USB adapter.
If you currently use a "dumb" broadband modem, supplied free by your ISP, then you can't use this with your wireless router. You'll have to buy a router with a broadband modem built in.
Can't comment on the Netgear kit - never used it.