Bah, graphics [lady of ill repute].
Seriously, IMO, 320x200, 256-color is a fine resolution... Though admitedly, it was what was standard when I started gaming... And a lot of these older games are older than many people here. I RECALL there are some hacks that can raise the game's resolution, that I recall seeing, but I never bothered with it 'cuz well, 320x200 is fine for me for it, and if I went any higher, my mind would expect anisotropic texture filtering and true full-scene anti-aliasing, like I'm used to any of my 3D accelerated games getting.
I guess I really am a bit of a [lady of ill repute] when it comes to graphics, but grant a free pass to anything running traditional VGA's 320x200x8bpp, because of how close that is to my heart.
And, um, how beastly does my hardware need to be to run it? It can run Bioshock smoothly...
It's much more about the CPU than graphics card, since emulation is quite CPU intensive; that old, simpler code becomes a real problem when for every operation it'd normally have to do, it has to run another few dozen just to 'translate' it.