LCDs are digital displays, and thus have discrete pixels that form a "native" resolution. For best quality, you'll want a display whose native resolution is either the exact resolution you want to run at, or an integer multiple of it. If you try to scale an image on an LCD whose native res is not an integer multiple of the source, it will use an interpolation algorithm to stretch the image to fit the screen, which will result in a loss of image quality.

1600x1200 would be perfect for 800x600, for example, while 1280x1024 will be better for 640x480 (although you'll get small black bars at the top and bottom because 480*2=960 instead of 1024).

Also, there will be no difference between the 17" and 19" monitors you listed, unless their upscaling algorithms are different.

Personally I'd go for 1600x1200 because 800x600 will look great, and 640x480 will have more pixels to be interpolated over (versus trying to interpolate 800x600 onto 1280x1024).

When you say "Old games = games that run only in 640x480 or 800x600" does that mean you will play Windows only games? Because if you are thinking of Dos games, most of these are using lower resolutions than that and then you just might run into trouble if the LCD does not support this resolution at all (not even interpolated).
With a 15" LCD I did not have problems ages ago with a mixture of Windows 95/WfW3.11/Dos.
I could be mistaken, though...

HunterZ, thx for the info, didn't know about the multiple thing. So if the native resolution of the screen is an integer multiple of the resolution of the game, than the image of the game won't get blured? Cool.

Dominus: Yes, old windows games, most of them 2D. For Dos games i plan to use DosBox and run them in a higher resolution.

Dopefish: Yes, assuming you set the monitor to perform aspect-correct scaling of the display: if it can stretch the source image by an integer multiple and have it fill up at least one axis of the monitor (while leaving black bars if necessary on the ends of the other axis) then it won't have to do any interpolation (which causes blurring), and you'll get a sharp image. This is because it will be able to use exact X-by-X squares of pixels on the monitor to represent single pixels from the source image.

As an example, an 800x600 game on a 1600x1200 monitor will use 2x2 squares of pixels to show each of the game's 800x600 pixels (800*2=1600, 600*2=1200).

640x480 on a 1600x1200 monitor, on the other hand, will use 2.5x2.5 squares of pixels (1600/640 = 2.5, 1200/480 = 2.5), but since you can't use half a pixel it will have to do some blurring to keep it from looking like crap.

find one that offers scaling options

Devros: If a use 1:1 scaling, the picture will be too small for my taste and i will also get black bars around it. Only a "keep aspect ratio and stretch it to full screen" option would help, with resolutions like 640x480 on a 1600x1200 screen. I will still get black bars, but it will be minimal.

who's this Devros guy 😉
If the monitor doesnt offer scaling options you'll be stuck with stretch image and nothing else because your using dos you wont be able to rely on graphics card drivers to change settings

Sorry Davros, my eyes play tricks on me...😀

Anyway, as i've said, for Dos games i will use DosBox.

It also depends on the video input you are using. My monitor would automatically stretch digital input in DOS.

Although I've got a 1680x1050 panel those lower resolutions are way too pixelated [not blurry] unless some FSAA is applied. 640x480 looks best on 14" screens. The common monitor size of those days. If you want to go retro mode a proper monitor is essential. I would have probably got settled with a CRT, if needed.