Oh ok, yea if you already have VGA out then that makes things much simpler, I forget a lot of them have it. I'd think it would still look better on a CRT computer monitor than an LCD, so that 19" you mentioned should look pretty good.
I'm not entirely sure if it would work on medium res games. Part of me thinks it would, but I'm not really too familiar with medium res games. Might be worth looking into, or picking one up cheap and trying it. I use mine for RGB modded retro consoles mostly. They support nearly everything.
EDIT: Correction here, I did a bit of research, I don't think they do work with medium res games. I looked around and it generally seems like they dont.