how do you connect to the net with you laptop, if directly then you simply plug that lead into a wireless router and you can use your laptop all over the house, and the ps3 will find the router and you can go straight online..
other than that read the manual or speak to someone at somewhere like pc world.
their should be a offical playstation adsl ethernet cable basically the thick cable with the telephone looking socket cant miss it. or go into your nearest computer shop and ask for the ethernet cable it should be a j1 cable.