The ICO "problem" is that it runs in low-resolution (actually, it runs in field rendered mode, but only updates at 30 fps and doesn't attempt to emulate 640x448). On an HDTV, it is quite pixelated looking (similar to running a low-res game on a PC monitor). For me, it looks both better yet worse on my HD set. When running low-res images on my older Toshiba 20" set, you would notice an excess of moire on the left and right sides. Due to the color scheme employed by ICO, it was quite present and damaged the image quality. On my HD set, however, the image quality is perfect...just pixelated. I think I actually prefer that...
It doesn't run at 320x***, though. Like I said, it uses field rendering. In a game like Ridge Racer V, it updates either odd or even scan lines each second. By moving back and forth quickly, it creates the impression of a high-res image. In FR games, pauses from loading often cause the image to look quite blocky for a split second. ICO's image quality is the same as that effect you see when pausing. It is not drawing odd AND even scanlines in the same fashion and you are simply seeing a 30 fps image that actually LOOKS like 640x224 rather than 448.
PS2 games, in general, do not look that good on HD. Certainly not bad (MUCH better than running something like this on a PC monitor), but not great. I've actually managed to make most of them look pretty darn nice, but it could be better.
SSX3 looks REALLY good, though. The colors used for the game combined with the sharp prog-scan output looks very sweet. Soul Calibur 2 PS2 also has (IMO) the best output of the three versions in 480p. Jak II actually doesn't look that hot in 480p as it is oddly low-res looking (even worse in 480i, obviously). It is perhaps the blockiest 480p game I have seen.
When talking about prog-scan games, I think GC actually has the best output of the three. The image quality is absolutely incredible on some games.
