i find that the Smart 2x filter paired with 1080p output is nice for 480p GC games. the Metroid Primes look pretty good this way.
N64 is a lost cause. even the above combo doesn't do much for most games. for me it is all about avoiding the massive input lag i'd get if i plugged the console directly to the TV (i have space issues so a CRT is completely out of the question)
Wow that made a pretty big difference on the Dreamcast. Much better. I'll try doing the same with GCN after the holiday.
Edit: I was able to test out the GCN this morning before work with a 480p game. It looks far better with this setting, but still a slight touch beneath the caliber of my HDTV's built-in scanner. Still, this is my only way to play DC in 480p at this point, and I'm finally happy with the image quality for that specific purpose.
Thanks Madao.