A moderate frustration about the Nintendo Wii is its stubborn refusal to recognize SD cards larger than 2GB in capacity. Given that larger, 4GB cards often support higher transfer rates - and, obviously, offer more storage - the frugal-fiends at Cheap Ass Gamer have come up with a system to create 4GB SD cards that, by pretending to be under 2GB, fool the Wii into accepting them.
The system involves filling up the 4GB SD card with dummy data so that the total free capacity is brought down under the acceptable 2GB limit. Before that happens, the Wii won't allow you to transfer or save anything to or from the memory; afterwards, it will. When you start to run out of space, you delete some of the dummy data: as long as the total free space remains less than 2GB, the card will continue to be recognized, even if it contains more than that amount of saved Wii data.
There's a full tutorial, together with some specially customized apps available to download which automatically create dummy 100MB blocks. Anyone still unconvinced should take a look at the speed tests, which showed up to 91-percent faster transfers from Wii to SD in some games when a 4.0 GB Transcend 133x card was used instead of a standard 2GB SanDisk for Wii card.