A few days ago, Joel linked to NFGForum's articles on why oldschool games don't look the same on LCD displays -- it's because old CRT sets' light guns created inadvertent anti-aliasing effects, scanlines created an illusion of greater detail, images could be arbitrarily scaled, and so on.
So how do you get it back, given that modern pixels are sharp, square, and contiguous? Fancy filters, of course! Ian Bogost reviews a version of Atari 2600 emulator Stella modified to render the display like an old TV:
In Enduro, the color bleed effect is evident again. Here you see not only how much more realistic the car sprite would have appeared on a television, but also how the multiple colored lines on the horizon would have blended with one another, creating a more credible sunset.
Despite being mighty impressive, the results in a live game are far more remarkable. Edward and his colleagues have done a fantastic job.
They are currently working with the maintainer of the free, open-source Stella emulator to patch their changes into the main build, where the effects will be available as a configurable option.
There are many techniques used to give a new (old) look to old sprites.
The debate over how to view these old games -- with the presentation technology emulated vs. "As the creator intended" -- serves as backdrop to vigorous discussions, over the technical minutiae of pixel rescaling.