> what if I dont have ythe HBC installed and I have a 3.4 Wii? is twilight hack going to work?
Yes it works great. As mentioned you need to follow the instructions and do the HBC install immediately after the Twilight gamesave install
[to clarify, the 3.4 system will only delete the Twilight data - not the HBC after it is installed]
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Deleting the HBC yourself is probably a good idea (along with any other "unauthorized" software).
In general if you send your console for service, you should plan that you may lose everything on it. That includes the HBC, any older version of the system software and in some rare cases the saved games.

Remember, they are trying to fix your hardware. They don't care as much for the stuff on the console. They will upgrade the firmware without your permission. That's a known issue: http://nintendo.joystiq.com/2008/06/...net-not-happy/
If they find other problems, they may totally reflash the memory.

So in general if you have important things on your Wii, back them up.
Good luck