Yes this computer should run Sims 3 and it's expansions without too many problems in high settings.
However with Sims 3, please keep in mind due to the game engine's quirks the game still suffers from micro-stutters and periodic slow downs. There is not a lot you can do to fix this.
Also the more content you add to the game, like custom content, game mods and store content the more the game will lag. This is due to the way the game handles additional content. Again, not much can be done to speed that up unfortunately.