It honestly depends on what budget you are on. If you already have a 460, it'll cost as little as $130 USD to get one, but SLI 560s will cost from $350 to $440 USD. Dual 460s will have no problem playing anything (including Crysis 2 DX11 Ultra) so there's no problem in getting one. However, you're going to have to replace the entire setup when another graphics upgrade is in order. But at that point, you might as well get a new rig.