I've gone into a lot of detail because Wii modding becomes addictive, and once you done the emulation stuff, you'll want to explore more. This is a long thread, but don't panic, you only need to do the first few steps.

If you can unzip files on your computer and copy them to an SD card, you can do the mod. If you have an SD card knocking about then you have everything you need to do the mod in a around 5 - 10 minutes. In fact, the amount of cool stuff you can do with a Wii will surprise you. Many people have a Wii console they no longer use, and it can be very quickly and easily modified to become a kick-ass emulation machine.