Just thought I'd point out that if you are only intending on using it for homebrew then you would get more gigs per pound with a USB pendrive, fook for fifty quid you could get a decent HDD.
Say for example you went to Argos (it's not the cheapest place to get either but hear me out)
For a 16gb SD card that will work with everything you'll be about £50
Well at argos you can get a 500GB HDD for that price (with a free 4gb pendrive too).
Looking at local shops in my area, you could get a 500GB HDD(plus free 4bg pendrive), an 8GB and have £5 change. Shopping online would get you an even better deal.
Unless there is a very specific reason to want an SD card then imho your mad for considering it
In my opinion you should upgrade to 4.2 (because in the future it might be harder to upgrade, or harder to find the required files, plus you can do more and faster) and then get a HDD because you can do all the same things with it that you can do with an SD card and more. You will also prolong the life of your Wii DVD drive which we all know is the weakest link in the Wii console.
The only reason to go with an SD card would be something like you want to also use it with a camera or something, if you don't have a reason like this you will regret this advise. You will regret it even more when your Wii drive dies.
