Whatever you do, don't update your Wii. As the poster above said, get ModMii, and use the option to download the files needed and generate a guide for you to re-hack your Wii as if it were a virgin (unhacked). You can safely do this, without the need to update your Wii, and will in turn save you the hassle of hacking 4.3 (which will require a certain game, depending on your Wii's region).
There is also really no point in hard-modding your Wii, since soft-modding can cover pretty much all the possible homebrew you can get anyways, including usage of backups either on DVD (if your Wii is compatible) or USB HDD.