You need a DSL Wireless Router if you have a cable service (Telewest / Virgin Media) or an ADSL Wireless Router if you have a service delivered down a telephone line (such as BT or Tiscali or AOL)
A 'crossover' cable would traditionally be used to link two PCs directly to one another but not a PC to a Router. You need an Ethernet (Network Cable) to link a PC to a Wireless Router.
Note:- Crossover Cable and Ethernet cables have the same RJ45 terminations on the end but two of the wires in a crossover cable are connected in 'reverse' (for want of a better word) so the cables have different functions, i.e. a crossover cable looks exactly like an Ethernet cable but is not the same.