360's CPU is a in-order mosquito on speed. It's potentially very fast but it's really, really hard to get it there. It has a ton of drawbacks to make it cheap but still potentially fast. Lots of developer effort required and ports from other platforms are not easy to pull off.
Yeah, I know that. But if you use peak performances (I guess), how much more powerful is the 360's CPU?
As for a magical HD spec? Nope. A Voodoo3 from 1999 can run 1280x720 just fine. Wii just isn't designed to allow for that much framebuffer. It's tailored to run 720x480 and they cost-optimized it in various ways around that limit. The eDRAM makes that optimization a critical thing. eDRAM is expensive.
Ah, yes. I forgot that old graphics cards can handle high resolutions (but without many effects, polygons, etc.).
See that's what I'm afraid of. That when Wii2 comes out, it'll have perhaps Xbox + level games but in 720p.