The microphones are generic. They aren't specifically designed for one system. So yes, if you purchased a Mic for your Xbox 360 GH games, it would in fact work for your Wii. Whether you purchased it for either GH or RB, it'll work regardless. As for your guitar. I assume you're asking for a USB guitar. For the actual games, it won't work, somebody would have to rewrite the game coding...and I don't think anybody would be willing. Same goes for USB drums. At most, somebody will add the detection of those instruments for the Guitarfun homebrew app.