If you're talking about how the games look chunky on PC monitors with WinUAE, you need to set scanlines on.
Most Amiga games were low-res non-interlaced, meaning every second line was not drawn. In WinUAE, it draws every line (duplicates the undrawn lines or "scan doubles") and so makes everything look like chunky crap. Enable scanlines and it will look better. (this has nothing to do with anti-aliasing)
