Are happy with your present USB modem?
Do you want to network a second computer?
If the answer to the first question is Yes and the answer to the second is No
Forget about ASDL2 modem/wireless router until you need it and stay with what you have
An ASDL2+ modem/wireless router is if you intend to network more than one computer to allow
file sharing plus an printer with the option to allow wireless access to wireless devices