i think there is a gross mis-understanding of current technology in the whole High-Definition 'buzz'.
Televisions that support SCART/RGB input, then you can guarentee that they will support 480p (4:3 720x480@60Hz), 720p (16:9 1280x720@60Hz) and 1080p (16:9 1920x1080@60Hz). Generally speaking only HD-Ready televisions support 480i, 720i and 1080i - but this isn't to say that SCART/RGB doesn't support this; in-fact a number of televisions before HDCP was even concepted support them.
As for the Nintendo Wii itself, unlike the competition their requirement is for developers to support 480p. This doesn't mean it doesn't also support 720p or 1080i resolutions that are the common ones being touted by Sony and Microsoft... in-fact it uses the exact same graphics chip R500 @ 500MHz as the Xbox 360.
The GameCube doesn't have a HDCP, however that console completely supports all of those resolutions. It also automatically detected the best resolution for your TV, and outputs to that. The Wii does the exact same.
So sure it doesn't have HDCP Output, but that doesn't mean it doesn't support these High-Definition resolutions.
People really need to get a bit more informed about this "new" technology. Also, on all Widescreen TVs pixel-scaling is built-in as standard... it isn't required on 4:3 sets, for the simple fact that DVDs and Television Channels output to this normally, and it's only in recent years that 16:9 has also been supported.
Technology is there to make our lives easier so we don't have to worry about all the technical side of things; unfortunately due to most people's removal from the technical side, companies are taking advantage that your adverage person knows nothing about what their TV supports.
Intel Core 2 Duo E6400, 512MB DDR2 667MHz, ATi Radeon X1900 XT 256MB PCI-E, Windows Vista Business / XP Professional SP2