Well here's a nice piece of info to know too on these component cables.
I held out a good 6+ months before getting them. My TV supports the cables, but it is NOT progressive scan, it's a 480i 27" Sony WEGA from 2002 with a 3D digital comb and optional widescreen. My brother has a HD set and he got the cables, said it did a HUGE difference on there, but I wasn't sure.
I eventually broke down and gave it a try and here's what I noticed changed just for example and i'll stick to NOT games since that Gamespot ROLLOVER says that well.
Using the AP news thread after I went smaller in size slightly beyond default it began to get twinkly and blurred on the old cable. When I got the new cable I could go down another couple sizes, and it wasn't still getting twinkly and blurred, it just was that my set wasn't progressive scan, widescreen, or large enough for me to read it fine...but stayed clear.
The same can be said for using the web browser where I saw even a nicer level of ability to drop it down in size and still be able to read, but in part that would depend on the sites choice of font as well, but even still images, web games, or whatever got a LOT sharper. The browser runs at 800x600 I found on a weird pop up that's non-descript at nintendo's page that covers wii...and with the new cable feels much more crisp with the cable.
To me it was worth the money, and I'm told on a widescreen HD set it even look 2-3x nicer than that just due to the upper resolutions those sets run at. ...and yes I think you worried about the black bars on the left/right they do vanish.