for the first time is to keep it simple - which at first sight isn't easy, as you've discovered.
With your NTL broadband service you'll need to use an ethernet router - one that has a WAN port which connects to your set-top box or standalone modem. Go for a 802.11g model, a Netgear WGR614 would be suitable.
The PC will need to have a conventional LAN adapter installed, and the other computer must of course have a wireless adapter. It's not essential for the adapters to be the same make.
Why so many models to choose from? That's like asking why there are so many TV's to choose from, it's called commercial competition.