Wii games only run in 480i/p.
Wii games: Super Mario Galaxy, Metroid Prime 3, Resident Evil 4, Zelda TP, SSX: Blur, Excite Truck, The Godfather, and Mario Kart Wii
PC games: Call of Duty 4, Halo 1, UT3, F.E.A.R., and The Orange Box.
PS3 games: Ratchet and Clank F.T.O.D., Resistance 2, Wipeout HD, and MGS4.
You will probably get better results by using component cables which provide a better signal directly to the TV (or AV receiver) than to use composite cables to an intermediate device which upscales.
From the linked site:
Finally Wii owners can play their Wii on digital TVís and experience the depth of colors and detail only available through digital HDMI.
I find this misleading. You could always play your Wii on a digital TV and experience the depth of colors and detail available at 480p. Upscaling cannot add detail that is not there. The only possible benefit for this is if you have no available component inputs and need to connect via HDMI.