The analogy to the Xbox is a tough one to make, since, like some other posters have already mentioned, the Xbox was top of its class last generation for graphics. The Wii is at the bottom this generation, so being able to best the last generation is somewhat of a moot point. Also, please keep in mind that although the Wii is easy to program, it's still not compatible with other platforms (except the GC of course). Both the Xbox and the Xbox360 are essentially an offset of the PC platform, and thus get a lot of benefit from that connection. Alternatively, the Wii is adversely affected by the fact that last gen's superstar (the PS2) is still lingering, and dragging the Wii down. Many publishers have (foolishly I might add) chosen to group their game development into 2 categories, SD & HD. They develop one game for the Wii/PS2 and another for the PS360. This hampers the Wii immensely from a graphical standpoint AND a game design view.
Hardware is only a means to enjoy great games!
