Nah, I bought a replacement case from Ebay for Ãƒâ€šÃ‚Â£30 and fits it lovely.
I only did it about 2 weeks ago, I did buy a clear one with blue lights originally but didn't like it.
My PS3 and 360 are both black so I thought I would blend it in with those.
My TV and dvd player are black too and the Wii stood out like a sore thumb so I bought a black case.
I thought it was pretty easy but I have been taking apart and re-assembling consoles for years, you need a tri-wing screwdriver and I think it will void warranty as if needed a repair Nintendo will see it has been opened but I know a few people who have returned chipped Wii consoles under warranty and have still had them fixed so shouldn't be a problem.