Native mode: 1600x1200

The image displayed is fine and very sharp.

1280x1024

The effect is not necessarily striking, but the image deteriorates markedly when you resize to 1280x1024. You can see it clearly, for instance, in the gunstock. A few small lines and a bolt tend to disappear.

1024x768

A bit more blurred than at 1280x1024.

800x600

Surprisingly, the worst interpolations are at 800x600, yet this setting is in proportion to the native resolution. Yet, as can easily be seen, the result is a disaster. Even if users who formerly used dodgy, blurred CRT monitors could opt for 1024x768, no sensible person would choose the 800x600 setting, neither for games nor any other application.

If you are very demanding as to image quality, only the native mode, 1600x1200, will satisfy you.