Check out click here for diagrams. You should be able to find an ADSL modem that does not use USB. A USB modem will not connect to the wireless routers I've seen. So, your equipment list:
ADSL Modem (non-USB type)
Wireless Laptop card
Connect the ADSL modem to the internet, then connect a network cable from the ADSL modem to the wireless router. Install the wireless card into the laptop, load the drivers and away you go.