For those concerned about running classic games on a 320x240 screen, let me shine some light on what the hardware on those original classics ran at.
- Snes/Genesis = 256×224 (Genesis native, SNES Progressive)
- NES/Master System = 256x224.
- Gameboy = 160×144
- GBA = 240×160
- Neo Geo Pocket = 256×256
- MSX = 256×192
- ZX Spectrum = 256×192
- ColecoVision = 256×192
- Atari 2600 = 192x160
- DOS games = mostly ran at 320x200
Basically anything made earlier than the SNES is running lower than 320x240.
- N64 and PSX had games that can run at 640x480, but a lot of them ran at 320x240 (NTSC standard).
But really, it's not that big of deal for those two systems since downs-scaling 3D graphics is much easier to make look better than 2D.
- Sega Saturn can output a display resolution of 320×224, but it's similar to the PSX, where some games were programmed to display at this res, and some were higher.
- CPS2 and CPS3 (games like Third Strike, Alien Vs. Predator, Super Street Fighter II, Marvel vs. Capcom) ran at 384 x 224, so there will be some scaling there.
- CPS1 (games like Street fighter II:Champion Edition, Ghosts and Goblins, 1942, Black Tiger, etc...) is at 320x224, so there will be a tiny bit of up-scaling there, but that is of course if you plan on full-screen stretching. Otherwise, you'd get borders, which IMO is completely acceptable for proper displaying.
- Neo Geo (MVS): 320×224
- Sega STV (games like Cotton, Radiant Silvergun, Die Hard arcade): 320x224 just like NEO GEO
- Sega System 32 (games like Golden Axe 1, Dynamite Dux, Shinobi) = again, 320 x 224
- Sega System 32 (games like Golden Axe:The Revenge of Death Adder...which isn't even properly emulated on PC!) : Same as above
- And so forth...
Most Arcade games made before the late-90's will be at 320x224 or lower.