I just found these two articles the first one is what ATI is saying about the Wii's graphical power and how we've yet too see it at full power. And the second is just a small article stating how much more powerfull the graphics are compared to the GCN. These came from my gamespy newsletter. Heres the links and the articles copied and pasted.
Here's the first article http://www.gamesindustry.biz/content_page.php?aid=17458
Swinimer talks 'Hollywood' chip versus Xbox 360 GPU
ATI executive John Swinimer has declared that the full capabilities of the Nintendo Wii have yet to be revealed, since we've only been given a taster of what the machine can do so far.
Speaking to GameDaily, Swinimer said: "I think what you saw [at E3] was just the tip of the iceberg of what the Hollywood chip can bring to the Nintendo Wii."
However, he declined to reveal specifics of the consoles technical capabilities, stating: "I really don't think that it's about the [specs]; I think it's about the innovation that it brings to the table - the motion-sensing, the always-on capability, which is really cool too - the fact that the chip is powerful enough and responsive enough to be there at a moment's notice. I think that's pretty cool for the average gamer."
Swinimer was hesitant to discuss how the Wii's Hollywood chip squares up to the Xbox 360 GPU, which is also provided by ATI: "They're different chips for different platforms and different uses. I don't think it's a fair comparison to put them on a chart. That's not what it's all about."
"I think if you focus on the capabilities that the chip will have for the average consumer, with the amazement and wow factor, I think that's the value that we bring."
Swinimer did confirm that ATI has been working very closely with Nintendo, and that "The team that worked on this chip also worked on the Flipper chip that was in GameCube. They've been working with Nintendo for a very long time so there's a great chemistry with the two teams working together."
Exactly how the Wii will compare to the GameCube in terms of power is not yet known. However, some developers estimate that the new console will run at around four times the speed of its predecessor, once both the CPU and GPU are factored in. More conservative estimates suggest the Wii will run at around double the speed of the GameCube.
And the second one http://games.slashdot.org/games/06/06/04/1729245.shtml
Gamespot and GameDaily have additional details on Nintendo's upcoming console. Gamespot reports on comments by Nintendo President Iwata that they were specifically not going for high-end graphics with the Wii. He goes on to say that some of their staff initially disagreed with the adoption of the Wiimote, but public and internal reaction has allayed the fears of detractors. GameDaily reports on comments from ATI, who says there is still a lot left to see from Wii's graphical output. What was shown at E3 was 'just the tip of the iceberg.'
From the article: "Industry sources have said that the Wii GPU would be moderately more powerful than the GameCube's GPU, but how much more we don't know. Conservative estimates from developers have placed the Wii console as a whole at 2 - 2.5 times more powerful than the GameCube."