Your choices seem compatible, but...
Will you do a lot of multitasking, or run VMs? The 4 core AMD processor you have is better for such tasks, while a 2 core i3 2120 will be better for games. It will also consume less power.
You can double check your power requirements using this link:http://www.extreme.outervision.com/psucalculatorlite.jsp
But I feel that a 350 watt power supply should be more than enough. Make sure you get a 80plus certified one.