Just now registered and for my first message I thought I'd check see if there's anyone else out there like me who owns a Wii but can't get Broadband?
I can't get broadband due to where I live, well that's what BT said anyway, but I have a friend who works at BT who told me otherwise. However, back to the point, I managed to download the first Wii Update today (the one that enables you to save games to the SD card).
However, it then went straight on to download another update, about 60-75MB!!! but my dial-up disconnected half way thru. Luckily, as many others were wondering, the firmware only gets installed once download is finished or that's how it seemed, as I had to pull the plug and got it back to Wii home screen and works fine, even still has the first update on ok. So incase your wondering yes it seems you can use Dial-up, and two, you can pull plug during download (but don't quote me on this!)
Also I am not using that silly Nintendo WiFi dongle thingy, as many have reported a crap range and problems with it.
If anyone's wondering whats better than the Nintendo dongle, I'm using a US Robotics 8054 WiFi router and all seems to work ok (just not the most straight forward thing to set up, lots of advanced settings, but that's what I like), even with DS, just it's really SLOOOOWWW with dial-up, worked better in my old house with BB obviously!!!