yes you will need to through one of two options...
1) wireless internet. If you have a router hooked up to a computer the receives your internet service the wii will be able to receive its signals.
2) non-wireless internet. I believe you will still need a router, but you also need a cord to attach from your router to your wii. I am pretty sure nintendo will have an adapter to hook that cord into your wii.
hope that clears some things up for you. if not just keep askin questions