It depends on the individual LCD screen, and how it does the interpolation... but don't expect miracles at any resolution other than the nominal one. My Acer monitor is not very good at this, though 
For the 1600x1200 monitor, it depends too of the interpolating algorithms: a "nearest neighbour" approach may give perfect sharpness (scaled 2x), but some models could smooth it out anyway. BTW, all 17" (and 19") non-wide LCDs I know of are native 1280x1024 (5:4 ratio)
Vintage Macs have no "panoramic" modes, thus the best one for my Acer is 1024x768, which only has to be interpolated horizontally, while the vertical resolution matches the panel's resolution (768 lines). Unfortunately, this wasn't a classic Mac resolution, which went from 832x624 (16") to 1152x870 (21") -- both supported at 75 Hz by my Acer, but far from ideal sharpness. More recent machines (Quadra 700, LC475...) with a suitable adapter do support 1024x769 (aka 19")
For the 1600x1200 monitor, it depends too of the interpolating algorithms: a "nearest neighbour" approach may give perfect sharpness (scaled 2x), but some models could smooth it out anyway. BTW, all 17" (and 19") non-wide LCDs I know of are native 1280x1024 (5:4 ratio)Vintage Macs have no "panoramic" modes, thus the best one for my Acer is 1024x768, which only has to be interpolated horizontally, while the vertical resolution matches the panel's resolution (768 lines). Unfortunately, this wasn't a classic Mac resolution, which went from 832x624 (16") to 1152x870 (21") -- both supported at 75 Hz by my Acer, but far from ideal sharpness. More recent machines (Quadra 700, LC475...) with a suitable adapter do support 1024x769 (aka 19")