This is a quote "if a game is running at 1024 x 768 x 32 bit colour, it takes 3MB for the screen rendering (times 2 for double buffer) plus another 3MB for z-buffer which totals 9MB just for the screen. If you're target system has a 32MB video card then you're left with 23MB for textures. A single 1024 x 1024 x 32bit colour texture takes 4MB of video ram + 1.333MB for mipmaps, which gives you room for only 4 textures of that size (also remember that the HUD/GUI images take up texture memory as well). If you use textures of 512 x 512 then they are 1MB + 0.333MB each, which allows you 17 textures of that size."

So how do they do it for "Far Cry" and "Oblivion" with tons of plant models, weapons, characters, etc?

So how large do you make your textures to get some decent detail for a rpg? What if the player decides to drop many items in a scene like Morrowind or Oblivion?