Hey Clipper, thanks for all your help.

I went for it, and it all went great.
However, my friend also updated, and while he hasn't bricked, I forgot to tell him to upgrade to the latest version of Homebrew first, and now his Homebrew Channel is gone (there's an empty slot on the Wii main menu where it used to be). What is the easiest way of getting it back? Just redownloading it in the same way as before? Or have we made a big mistake, and there's no getting it back?
If we just have to redownload it, where do I start? Would you recommend any simple step-by-step instructions? I'm assuming that some of the stuff required to download Homebrew will still be on the Wii/SD card, and I don't want to risk screwing anything up by downloading anything a second time...
I apologise for my cluelessness, and asking you so much, but we really are naieve when it comes to this. :-( But once this is sorted out, that's both of us completely sorted.