how can i connect wii system online?

i'm very interested in buying a wii , but i want to know if i can connect it online with an ethernet cable or do i have to buy the usb wifi adapter?.......if so is it seemless or what ?.....thanks for any help

1) If you have a router, you just go on your Wii and click "Look for Hotspot/Router (W/e its called)". You click connect and your online.

2) If you dont have a router, you can buy a LAN Adapter (Wire from the Wii to an ethernet cable) or buy a Nintendo WiFi Connector for $40, and you do the same thing as #1.