Hm, also, the wireless routers aren't that expensive (at least mine one), and are safer to use with your DS, since if I remember right, the USB adapter takes the same DS input where the charger is, and as wi-fi makes your battery go down faster, it's not good being unplugged from the charger.
And it's good to remember, that wi-fi routers can be plugged in your normal router, so you can keep the same internet account.
You don't or you don't think you use a wireless router? Is there a cord coming out the back of your computer that's hooked into a box with flashing lights on it?
It also normally have an antenna, that sends wi-fi signal