Yes, this desktop will run Sims fine on high settings.
Please be aware that you may still run into lag and slowdowns in Sims 3 from time to time due to the way game is. This will happen mostly in Create a Style, and Build/Buy Mode.
The more you load up your game with custom content and/or Sims 3 Store content it will effect the performance of the game as well. So please take that into consideration.
The graphics card this pc has will definitely run at high settings, but you may be able to upgrade it to a newer graphics card later on.