The results of the mainstream graphics cards suggest that Metro 2033 is not really designed for them. Even the Radeon HD 5750 at 1280x1024 is not fast enough to deliver a playable speed. The rest of the cards in this category are no better than 15-20 fps, making you lower the graphics quality settings or discard such products altogether. The GeForce GTS 250 should be given credit for keeping a good pace despite its respectable age, but the only feat it is capable of is to beat the obviously low-end Radeon HD 5670 which is not positioned as a really fast gaming solution. The graphics cards like Radeon HD 5570 and GeForce GT 240, let alone GeForce GT 220, can only act as hardware accelerators of a beautiful slideshow in this game.
So, there is only one graphics card you may want to try to play Metro 2033 on by lowering the graphics quality settings. It is the Radeon HD 5750. The rest of the mainstream solutions are hopeless here.