[email protected]@ is absolutly correct Digit broadband routers are totally different to modems and as said most companies supply them for free when you sign up for a year. The thing you need is a spare USB port as this is what they tend to supply however if you don't have a spare one it fairly easy to add more or to buy an internal router. Apart from that the only thing else you really need to know is, is your PC fast enough to run a router. The recommended minimum spec for Wanadoo for example is
Digit, yes, you will be able to but if you're going down the P2P route for it you'll need to be vigilant about your firewall, AV and anti-crudware software. In fact with broadband you'll need to be pretty vigilant about all that stuff anyway.