I realized today that from a horsepower perspective, the Wii is more powerful than the GC in the same way, the same amount, as the PS2 is more powerful than the Dreamcast.

In both scenarios, multiply the weaker system's clock speeds by 1.5, and more or less double the Ram, and there you have it.

Dreamcast              PS2
200MHz cpu ->     300MHz cpu (1.5 x)
100MHz gpu ->     150MHz gpu (1.5 x)
16MB memory ->  32MB memory (2 x)

GameCube             Wii
485MHz cpu ->      729MHz cpu (1.5 x)
162MHz gpu ->      243MHz gpu (1.5 x)
40MB memory ->   104MB memory (>2 x)

I know this is ballpark city, since these are only basic details. A processor with twice the clock speed may take twice as many cycles to do the same thing as another processor, afterall, so this is only part of the picture.

Nonetheless, there is a fairly strong connection here. Maybe we should expect the Wii to be about as superior to the GC as the PS2 is to the Dreamcast, to keep our hopes realistic. Think of Shadow of the Colossus vs. Crazy Taxi...maybe in 5 years we'll have [some good looking Wii game] vs. Smash Bros. Melee, with a similar leap in graphics.