The ViewSonic N4 and MSI-8876 TV@NYWHERE PCI card don't support component input, so you can't get progressive scan. If your looking to get progressive scan from a converter box and don't want to do the cable mod you would have to go with the ViewSonic NextVision N6 ,
ViewSonic page. Here's a review of it -
Click here. It costs around $350.
If your not going to want to use progressive mode, then I would suggest getting a PCI video input card (the MSI-8876 TV@NYWHERE PCI looks good) with a Gamecube S-Video cable and use either of the following programs to make the video sharp and smooth.
DScalerFlyDSThe first one is a freeware program. The second costs $30 if you register it.
I've used both and found FlyDS to be the smoothest.
Both programs de-interlace the input video from the gamecube and keep the video from tearing and looking like crap. They also have different filters that can be used to enhance the video. Most video input cards don't have built-in de-interlacing code in their software, so video from the software that comes with the cards look horrible.
I've been using FlyDS for about 2 weeks now and it has made a huge difference in the video quailty from my cube. I'm only using the RCA cable and it looks better than on my TV. I'm sure using the S-Video cable would only make things better.