a broadband connection with several computers you can do it in different ways.
A wireless broadband router can come with a broadband modem built in, and you can connect all the machines to it using CAT5 ethernet cable. If you do that you will need to install an ethernet Network Interface Card (NIC) in each computer, and run the cable from each card to the router, which will have ethernet ports at the back.
Alternatively, you could create a wireless network, using the same router, but with wireless network adapters in each machine - either internal card types or external USB adapters.
The cable method will be cheaper, because NICs cost less than wireless adapters, but you should factor in the cost of the cable, your time for running it, and the fact that you may not want network cable running around skirting boards/under floorboards.
You could buy a router that doesn't have its own modem, in which case you can plug your Speedtouch 330 into it, but be sure to get one that has the correct USB connector for the modem - they don't all have it.