"Wii Video 9" & "PS3 Video 9", two free apps for converting your divx/xvid etc. videos into a format playable by the Wii/PS3.
http://www.redkawa.com/videoconverters/wiivideo9/
http://www.redkawa.com/videoconverters/ps3video9/
Although, as the Wii only supports Motion JPEG (M-JPEG), your e.g. nice small 350MB xvids end up rather large... so you better get a big SD card.