ok, first thing is what sort of broadband? cable or adsl basically (adsl is when you use your standard phone line).
now, if your ISP sends you a broadband modem (or you already have it), then check the connection that it gives you. ideally it'll connect to your PC with an ethernet cable (looks like a thick phone cable, with phone cable endings). if it does this, then all you need is a standard wireless router. if however your modem that you have been supplied with has a USB out cable to plug into your PC, then it's easier to buy a 'wireless router + modem' in one (a standard wireless router will be wanting ethernet input, not USB). but here, you need to make sure that the modem built-in to the router is for either a cable or ADSL connection (hence why I asked earlier).
then you can just connect your PC with a cable (probably supplied with the router), and then the laptops will be able to connect wirelessly.
example of a wireles router + ADSL modem in one:
http://www.scan.co.uk/Products/ProductInfo.asp ?WebProductID=91316
if your laptops aren't already wireless enabled, you can get something like this to plug in and make them work:
http://www.scan.co.uk/Products/ProductInfo.asp ?WebProductID=150692